# Networking Guide	{#idm22251648}

## Configuration and Administration of networking for Fedora 20

###

### Stephen Wadeley

Red Hat<br />
 Engineering Content Services<br />

&lt;[swadeley@redhat.com](mailto:swadeley@redhat.com)&gt;

Copyright © 2014 Red Hat, Inc. and others.

The text of and illustrations in this document are licensed by Red Hat under a Creative Commons Attribution–Share Alike 3.0 Unported license ("CC-BY-SA"). An explanation of CC-BY-SA is available at <http://creativecommons.org/licenses/by-sa/3.0/>. The original authors of this document, and Red Hat, designate the Fedora Project as the "Attribution Party" for purposes of CC-BY-SA. In accordance with CC-BY-SA, if you distribute this document or an adaptation of it, you must provide the URL for the original version.

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Abstract

The _Networking Guide_ documents relevant information regarding the configuration and administration of network interfaces, networks and network services in Fedora 20. It is oriented towards system administrators with a basic understanding of Linux and networking.

This book is based on the _Deployment Guide_ from Red Hat Enterprise Linux 6. The chapters related to networking were taken from the Deployment Guide to form the foundation for this book.

----

# Preface	{#idp61283136}

The _Networking Guide_ contains information on how to use the networking related features of Fedora 20.

This manual discusses many intermediate topics such as the following:

* Setting up a network (from establishing an Ethernet connection using NetworkManager to configuring channel bonding interfaces).

* Configuring `DHCP`, BIND, and `DNS`.

## 1\. Target Audience	{#sec-Preface-Target_Audience}

The _Networking Guide_ assumes you have a basic understanding of the Fedora operating system. If you need help with the installation of this system, see the _Fedora 20 Installation Guide_.

This guide is not aimed exclusively at experienced Linux system administrators. The authors of this book have attempted to cater for a wider audience as more and more organizations and users become subscribers to Red Hat, Inc. At the same time we are aware of the need not to allow seemingly trivial information to get in the way of the tasks. Your feedback on how well we have met this goal is welcome.

## 2\. About This Book	{#sec-Preface-About_this_book}

The _Networking Guide_ is based on the networking material in the [_Red Hat Enterprise Linux 6 Deployment Guide_](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/index.html). It also retains the information on `DHCP` and `DNS` servers from the [Part II, “Servers”](#part-Servers "Part II. Servers") section. Most of the non-networking related material from the _Red Hat Enterprise Linux 6 Deployment Guide_ guide can now be found in the _Fedora 20 System Administrator's Guide_ except for reference material, such as that found in the appendices of the Deployment Guide. Reference material is now in a separate guide, the _Fedora 20 System Administrator's Reference Guide_.

## 3\. What's new in Fedora 20	{#sec-Whats-New}

_Network Teaming_ has been introduced as an alternative to bonding for link aggregation. It is designed to be easy to maintain, debug and extend. For the user it offers performance and flexibility improvements and should be evaluated for all new installations.

A new command-line tool, nmcli, has been introduced to allow users and scripts to interact with NetworkManager. A simple curses-based user interface for NetworkManager, **nmtui**, is also available.

A number of improvements have been made to NetworkManager to make it more suitable for use in server applications. In particular, NetworkManager no longer watches for configuration file changes by default, such as those made by editors or deployment tools. It allows administrators to make it aware of external changes through the **nmcli connection reload** command. Changes made through NetworkManager's D-Bus API or with nmcli are still effective immediately.

Not included in this guide, but of interest to network administrators, is the new _Open Linux Management Infrastructure_ or OpenLMI project. This is an implementation of open industry standards for remote system management, which includes an agent for networking. See the _Fedora 20 System Administrator's Guide_ for information on the OpenLMI Networking Provider.

## 4\. How to Read this Book	{#sec-Preface-Book_Organization}

This manual is divided into the following main categories:

[Part I, “Networking”](#part-Networking "Part I. Networking")
:    This part describes how to configure the network on Fedora.

[Chapter 1, _Introduction to Fedora Networking_](#ch-Introduction_to_Fedora_Networking "Chapter 1. Introduction to Fedora Networking") explains the default networking service, NetworkManager, and the various graphical and command-line tools that can be used to interact with NetworkManager. These include, an associated command-line configuration tool, nmcli, and two graphical user interface tools, control-center and nm-connection-editor. Read this chapter to learn more about the many ways the NetworkManager daemon can be used.

[Chapter 2, _Configure Networking_](#ch-Configure_Networking "Chapter 2. Configure Networking") covers static and dynamic interface settings, selecting network configuration methods, using NetworkManager with graphical and command-line user interfaces. Read this chapter to learn about configuring network connections.

[Chapter 3, _Configure Host Names_](#ch-Configure_Host_Names "Chapter 3. Configure Host Names") covers static, pretty, and transient host names and their configuration using hostnamectl. Read this chapter to learn more about configuring host names on local and remote systems.

[Chapter 4, _Configure Network Bonding_](#ch-Configure_Network_Bonding "Chapter 4. Configure Network Bonding") covers the configuring and use of bonded network connections. Read this chapter to learn about the configuring of network bonds using graphical and command-line user interfaces.

[Chapter 5, _Configure Network Teaming_](#ch-Configure_Network_Teaming "Chapter 5. Configure Network Teaming") covers the configuring and use of teamed network connections. Read this chapter to learn about the configuring of network teams using graphical and command-line user interfaces.

[Chapter 6, _Configure Network Bridging_](#ch-Configure_Network_Bridging "Chapter 6. Configure Network Bridging") covers the configuring and use of network bridges. Read this chapter to learn about the configuring of network bridges using graphical and command-line user interfaces.

[Chapter 7, _Configure 802.1Q VLAN tagging_](#ch-Configure_802_1Q_VLAN_Tagging "Chapter 7. Configure 802.1Q VLAN tagging") covers the configuring and use of virtual private networks, VLANs, according to the 802.1Q standard. Read this chapter to learn about the configuring of VLANs using graphical and command-line user interfaces.

[Chapter 8, _Consistent Network Device Naming_](#ch-Consistent_Network_Device_Naming "Chapter 8. Consistent Network Device Naming") covers consistent network device naming for network interfaces, a feature that changes the name of network interfaces on a system in order to make locating and differentiating the interfaces easier. Read this chapter to learn about this feature and how to enable or disable it.

[Part II, “Servers”](#part-Servers "Part II. Servers")
:    This part discusses how to set up servers normally required for networking.

[Chapter 9, _DHCP Servers_](#ch-DHCP_Servers "Chapter 9. DHCP Servers") covers the installation of a Dynamic Host Configuration Protocol (`DHCP`) server and client. Read this chapter if you need to configure `DHCP` on your system.

[Chapter 10, _DNS Servers_](#ch-DNS_Servers "Chapter 10. DNS Servers") covers the Domain Name System (`DNS`), explains how to install, configure, run, and administer the BIND `DNS` server. Read this chapter if you need to configure a `DNS` server on your system.

For topics related to network configuration but not listed above, such as configuring GRUB to enable serial links and the use of virtual console terminals, see the _Fedora 20 System Administrator's Guide_.

For topics related to servers but not listed above, such as configuring Network Time Protocol (`NTP`) and Precision Time Protocol (`PTP`), see the _Fedora 20 System Administrator's Guide_.

## 5\. Document Conventions	{#idm31185920}

This manual uses several conventions to highlight certain words and phrases and draw attention to specific pieces of information.

### 5\.1. Typographic Conventions	{#idp4553840}

Four typographic conventions are used to call attention to specific words and phrases. These conventions, and the circumstances they apply to, are as follows.

`Mono-spaced Bold`

Used to highlight system input, including shell commands, file names and paths. Also used to highlight keys and key combinations. For example:

> To see the contents of the file `my_next_bestselling_novel` in your current working directory, enter the **cat my\_next\_bestselling\_novel** command at the shell prompt and press **Enter** to execute the command.

The above includes a file name, a shell command and a key, all presented in mono-spaced bold and all distinguishable thanks to context.

Key combinations can be distinguished from an individual key by the plus sign that connects each part of a key combination. For example:

> Press **Enter** to execute the command.
>
> Press **Ctrl**+**Alt**+**F2** to switch to a virtual terminal.

The first example highlights a particular key to press. The second example highlights a key combination: a set of three keys pressed simultaneously.

If source code is discussed, class names, methods, functions, variable names and returned values mentioned within a paragraph will be presented as above, in `mono-spaced bold`. For example:

> File-related classes include `filesystem` for file systems, `file` for files, and `dir` for directories. Each class has its own associated set of permissions.

Proportional Bold

This denotes words or phrases encountered on a system, including application names; dialog-box text; labeled buttons; check-box and radio-button labels; menu titles and submenu titles. For example:

> Choose System → Preferences → Mouse from the main menu bar to launch Mouse Preferences. In the Buttons tab, select the Left-handed mouse check box and click Close to switch the primary mouse button from the left to the right (making the mouse suitable for use in the left hand).
>
> To insert a special character into a gedit file, choose Applications → Accessories → Character Map from the main menu bar. Next, choose Search → Find… from the Character Map menu bar, type the name of the character in the Search field and click Next. The character you sought will be highlighted in the Character Table. Double-click this highlighted character to place it in the Text to copy field and then click the Copy button. Now switch back to your document and choose Edit → Paste from the gedit menu bar.

The above text includes application names; system-wide menu names and items; application-specific menu names; and buttons and text found within a GUI interface, all presented in proportional bold and all distinguishable by context.

**_`Mono-spaced Bold Italic`_** or _`Proportional Bold Italic`_

Whether mono-spaced bold or proportional bold, the addition of italics indicates replaceable or variable text. Italics denotes text you do not input literally or displayed text that changes depending on circumstance. For example:

> To connect to a remote machine using ssh, type **ssh _`username`_@_`domain.name`_** at a shell prompt. If the remote machine is `example.com` and your username on that machine is john, type **ssh john@example.com**.
>
> The **mount -o remount _`file-system`_** command remounts the named file system. For example, to remount the `/home` file system, the command is **mount -o remount /home**.
>
> To see the version of a currently installed package, use the **rpm -q _`package`_** command. It will return a result as follows: **_`package-version-release`_**.

Note the words in bold italics above: username, domain.name, file-system, package, version and release. Each word is a placeholder, either for text you enter when issuing a command or for text displayed by the system.

Aside from standard usage for presenting the title of a work, italics denotes the first use of a new and important term. For example:

> Publican is a _DocBook_ publishing system.

### 5\.2. Pull-quote Conventions	{#idm15007152}

Terminal output and source code listings are set off visually from the surrounding text.

Output sent to a terminal is set in `mono-spaced roman` and presented thus:

	books        Desktop   documentation  drafts  mss    photos   stuff  svn
	books_tests  Desktop1  downloads      images  notes  scripts  svgs

Source-code listings are also set in `mono-spaced roman` but add syntax highlighting as follows:

	package org.jboss.book.jca.ex1;

	import javax.naming.InitialContext;

	public class ExClient
	{
	   public static void main(String args[])
	       throws Exception
	   {
	      InitialContext iniCtx = new InitialContext();
	      Object         ref    = iniCtx.lookup("EchoBean");
	      EchoHome       home   = (EchoHome) ref;
	      Echo           echo   = home.create();

	      System.out.println("Created Echo");

	      System.out.println("Echo.echo('Hello') = " + echo.echo("Hello"));
	   }
	}

### 5\.3. Notes and Warnings	{#idm17266176}

Finally, we use three visual styles to draw attention to information that might otherwise be overlooked.

### Note

Notes are tips, shortcuts or alternative approaches to the task at hand. Ignoring a note should have no negative consequences, but you might miss out on a trick that makes your life easier.

### Important

Important boxes detail things that are easily missed: configuration changes that only apply to the current session, or services that need restarting before an update will apply. Ignoring a box labeled “Important” will not cause data loss but may cause irritation and frustration.

### Warning

Warnings should not be ignored. Ignoring warnings will most likely cause data loss.

## 6\. Feedback	{#sec-Preface-Feedback}

If you find a typographical error in this manual, or if you have thought of a way to make this manual better, we would love to hear from you! Please submit a report in [Bugzilla](http://bugzilla.redhat.com/) against the product Fedora Documentation.

When submitting a bug report, be sure to provide the following information:

* Manual's identifier: `networking-guide`

* Version number: `20`

If you have a suggestion for improving the documentation, try to be as specific as possible when describing it. If you have found an error, please include the section number and some of the surrounding text so we can find it easily.

## 7\. Acknowledgments	{#pref-Acknowledgments}

Certain portions of this text first appeared in the _Red Hat Enterprise Linux 6 Deployment Guide_, copyright © 2014 Red Hat, Inc., available at [https://access.redhat.com/site/documentation/en-US/Red\_Hat\_Enterprise\_Linux/6/html/Deployment\_Guide/index.html](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/index.html).

# Part I. Networking	{#part-Networking}

This part describes how to configure the network on Fedora.

## Chapter 1. Introduction to Fedora Networking	{#ch-Introduction_to_Fedora_Networking}

## 1\.1. How this Book is Structured	{#sec-How_this_Book_is_Structured}

All new material in this book has been written and arranged in such a way as to clearly separate introductory material, such as explanations of concepts and use cases, from configuration tasks. The authors hope that you can quickly find configuration instructions you need, while still providing some relevant explanations and conceptual material to help you understand and decide on the appropriate tasks relevant to your needs. Where material has been reused from the [_Red Hat Enterprise Linux 6 Deployment Guide_](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/index.html), it has been reviewed and changed, where possible, to fit this idea of separating concepts from tasks.

The material is grouped according to the goal rather than the method. Instructions on how to achieve a specific task using different methods are grouped together. This is intended to make it easier for you to find the information on how to achieve a particular task or goal, and at the same time allow you to quickly see the different methods available.

In each chapter, the configuration methods will be presented in the following order: A graphical user interface (GUI) method, such as the use of nm-connection-editor or control-network to direct `NetworkManager`, then NetworkManager's command-line tool nmcli, and then finally methods using the command line and configuration files. The command line can be used to issue commands and to compose or edit configuration files, therefore the use of the ip commands and configuration files will be documented together.

## 1\.2. Introduction to NetworkManager	{#sec-Introduction_to_NetworkManager}

As of Fedora 20, the default networking service is provided by `NetworkManager`, which is a dynamic network control and configuration daemon that attempts to keep network devices and connections up and active when they are available. The traditional `ifcfg` type configuration files are still supported. See [Section 1.6, “NetworkManager and the Network Scripts”](#sec-NetworkManager_and_the_Network_Scripts "1.6. NetworkManager and the Network Scripts") for more information.

Table 1.1. A Summary of Networking Tools and Applications

|Application or Tool|Description|
|-|
|NetworkManager|The default networking daemon|
|nmtui|A simple curses-based text user interface (TUI) for NetworkManager|
|nmcli|A command-line tool provided to allow users and scripts to interact with NetworkManager|
|control-center|A graphical user interface tool provided by the GNOME Shell|
|nm-connection-editor|A GTK+ 3 application available for certain tasks not yet handled by control-center|

<br />

`NetworkManager` can be used with the following types of connections: Ethernet, VLANs, Bridges, Bonds, Teams, Wi-Fi, mobile broadband (such as cellular 3G), and IP-over-InfiniBand. For these connection types, `NetworkManager` can configure network aliases, `IP` addresses, static routes, `DNS` information, and VPN connections, as well as many connection-specific parameters. Finally, `NetworkManager` provides an API via D-Bus which allows applications to query and control network configuration and state.

## 1\.3. Installing NetworkManager	{#sec-Installing_NetworkManager}

NetworkManager is installed by default on Fedora. If necessary, to ensure that it is, run the following command as the `root` user:

	~]# **yum install NetworkManager**

For information on user privileges and gaining privileges, see the _Fedora 20 System Administrator's Guide_.

### 1\.3.1. The NetworkManager Daemon	{#sec-The_NetworkManager_Daemon}

The NetworkManager daemon runs with root privileges and is, by default, configured to start up at boot time. You can determine whether the NetworkManager daemon is running by entering this command:

	~]$ **systemctl status NetworkManager**
	NetworkManager.service - Network Manager
	   Loaded: loaded (/lib/systemd/system/NetworkManager.service; enabled)
	   Active: active (running) since Fri, 08 Mar 2013 12:50:04 +0100; 3 days ago

The **systemctl status** command will report NetworkManager as `Active: inactive (dead)` if the NetworkManager service is not running. To start it for the current session run the following command as the root user:

	~]# **systemctl start NetworkManager**

Run the **systemctl enable** command to ensure that NetworkManager starts up every time the system boots:

	~]# **systemctl enable NetworkManager**

For more information on starting, stopping and managing services, see the _Fedora 20 System Administrator's Guide_.

### 1\.3.2. Interacting with NetworkManager	{#sec-Interacting_with_NetworkManager}

Users do not interact with the NetworkManager system service directly. Instead, users perform network configuration tasks via graphical and command-line user interface tools. The following tools are available in Fedora:

1. A graphical user interface tool called control-center, provided by GNOME, is available for desktop users. It incorporates a Network settings tool. It start it, press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**.

1. A command-line tool, nmcli, is provided to allow users and scripts to interact with NetworkManager. Note that nmcli can be used on GUI-less systems like servers to control all aspects of NetworkManager. It is on an equal footing with the GUI tools.

1. The GNOME Shell also provides a network icon in its Notification Area representing network connection states as reported by NetworkManager. The icon has multiple states that serve as visual indicators for the type of connection you are currently using.

1. A graphical user interface tool called control-center, provided by the GNOME Shell, is available for desktop users. It incorporates a Network settings tool. To start it, press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The **Super** key appears in a variety of guises, depending on the keyboard and other hardware, but often as either the Windows or Command key, and typically to the left of the Spacebar.

1. A graphical user interface tool, nm-connection-editor, is available for certain tasks not yet handled by control-center. To start it, press the **Super** key to enter the Activities Overview, type **network connections** or **nm-connection-editor** and then press **Enter**.

## 1\.4. Network Configuration Using the Command Line Interface (CLI)	{#sec-Network_Config_Using_CLI}

The commands for the ip utility, sometimes referred to as iproute2 after the upstream package name, are documented in the `man ip(8)` page. The package name in Fedora is iproute. If necessary, you can check that the ip utility is installed by checking its version number as follows:

	~]$ **ip -V**
	ip utility, iproute2-ss130716

The ip commands can be used to add and remove addresses and routes to interfaces in parallel with NetworkManager, which will preserve them and recognize them in nmcli, nmtui, control-center, and the D-Bus API.

### Note

Note that ip commands given on the command line will not persist after a system restart.

Examples of using the command line and configuration files for each task are included after explaining the use of one of the graphical user interfaces to NetworkManager, namely, control-center and nm-connection-editor.

## 1\.5. Network Configuration Using NetworkManager's CLI (nmcli)	{#sec-Network_Config_Using_nmcli}

The NetworkManager command-line tool, nmcli, provides a command line way to configure networking by controlling NetworkManager. It is installed, along with NetworkManager, by default. If required, for details on how to verify that NetworkManager is running, see [Section 1.3.1, “The NetworkManager Daemon”](#sec-The_NetworkManager_Daemon "1.3.1. The NetworkManager Daemon").

Examples of using the nmcli tool for each task will be included where possible, after explaining the use of graphical user interfaces and other command line methods. See [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli") for an introduction to nmcli.

## 1\.6. NetworkManager and the Network Scripts	{#sec-NetworkManager_and_the_Network_Scripts}

In previous Red Hat Enterprise Linux releases, the default way to configure networking was using _network scripts_. The term _network scripts_ is commonly used for the script `/etc/init.d/network` and any other installed scripts it calls. The user supplied files are typically viewed as configuration, but can also be interpreted as an amendment to the scripts.

Although NetworkManager provides the default networking service, Red Hat developers have worked hard to ensure that scripts and NetworkManager cooperate with each other. Administrators who are used to the scripts can certainly continue to use them. We expect both systems to be able to run in parallel and work well together. It is expected that most user shell scripts from previous releases will still work. Red Hat recommends that you test them first.

### Running Network Script	{#bh-Running_Network_Script}

Run the script **only** with the systemctl utility which will clear any existing environment variables and ensure clean execution. The command takes the following form:

	**systemctl `start|stop|restart|status` network**

**Do not run** any service by calling **/etc/init.d/_`servicename`_ `start|stop|restart|status`** directly.

Note that in Red Hat Enterprise Linux 7, NetworkManager is started first, and `/etc/init.d/network` checks with NetworkManager to avoid tampering with NetworkManager's connections. NetworkManager is intended to be the primary application using sysconfig configuration files and `/etc/init.d/network` is intended to be secondary, playing a fallback role.

The `/etc/init.d/network` script is not event-driven, it runs either:

1. manually (by one of the **systemctl** commands **`start|stop|restart` network**),

1. on boot and shutdown if the network service is enabled (as a result of the command **systemctl enable network**).

It is a manual process and does not react to events that happen after boot. Users can also call the scripts `ifup` and `ifdown` manually.

### Custom Commands and the Network Scripts	{#bh-Custom_Commands_and_the_Network_Scripts}

Custom commands in the scripts `/sbin/ifup-local`, `ifdown-pre-local`, and `ifdown-local` are only executed when those devices are controlled by the `/etc/init.d/network` service. If you modified the initscripts themselves (for example, `/etc/sysconfig/network-scripts/ifup-eth`) then those changes would be overwritten by an initscripts package update. Therefore it is recommend that you avoid modifying the initscripts directly and make use of the `/sbin/if*local` scripts, so that your custom changes will survive package updates. The initscripts just check for the presence of the relevant `/sbin/if*local` and run them if they exit. The initscripts do not place anything in the `/sbin/if*local` scripts, nor does the initscripts RPM (or any package) own or modify those files.

There are ways to perform custom tasks when network connections go up and down, both with the old network scripts and with NetworkManager. When NetworkManager is enabled, the `ifup` and `ifdown` script will ask NetworkManager whether NetworkManager manages the interface in question, which is found from the “DEVICE=” line in the `ifcfg` file. If NetworkManager does manage that device, and the device is not already connected, then `ifup` will ask NetworkManager to start the connection.

* If the device is managed by NetworkManager and it **is** already connected, nothing is done.

* If the device is not managed by NetworkManager, then the scripts will start the connection using the older, non-NetworkManager mechanisms that they have used since the time before NetworkManager existed.

If you are calling "`ifdown`" and the device is managed by NetworkManager, then `ifdown` will ask NetworkManager to terminate the connection.

The scripts dynamically check NetworkManager, so if NetworkManager is not running, the scripts will fall back to the old, pre-NetworkManager script-based mechanisms.

## 1\.7. Network Configuration Using sysconfig Files	{#sec-Network_Configuration_Using_sysconfig_Files}

The `/etc/sysconfig/` directory is a location for configuration files and scripts. Most network configuration information is stored there, with the exception of VPN, mobile broadband and PPPoE configuration, which are stored in `/etc/NetworkManager/` subdirectories. Interface specific information for example, is stored in `ifcfg` files in the `/etc/sysconfig/network-scripts/` directory.

The file `/etc/sysconfig/network` is for global settings. Information for VPNs, mobile broadband and PPPoE connections is stored in `/etc/NetworkManager/system-connections/`.

In Fedora, when you edit an `ifcfg` file, NetworkManager is not automatically aware of the change and has to be prompted to notice the change. If you use one of the tools to update NetworkManager profile settings, then NetworkManager does not implement those changes until you reconnect using that profile. For example, if configuration files have been changed using an editor, NetworkManager must be told to read the configuration files again. To do that, issue the following command as `root`:

	~]# **nmcli connection reload**

The above command reads all connection profiles. Alternatively, to reload only one changed file, ``ifcfg-_`ifname`_``, issue a command as follows:

	~]# **nmcli con load /etc/sysconfig/network-scripts/ifcfg-_`ifname`_**

The command accepts multiple file names. These commands require `root` privileges. For more information on user privileges and gaining privileges, see the _Fedora 20 System Administrator's Guide_ and the `su(1)` and `sudo(8)` man pages.

Changes made using tools such as nmcli do not require a reload but do require the associated interface to be put down and then up again. That can be done by using commands in the following format:

	nmcli dev disconnect _`interface-name`_

Followed by:

	nmcli con up _`interface-name`_

NetworkManager does not trigger any of the network scripts, though the network scripts will try to trigger NetworkManager if it is running when `ifup` commands are used. See [Section 1.6, “NetworkManager and the Network Scripts”](#sec-NetworkManager_and_the_Network_Scripts "1.6. NetworkManager and the Network Scripts") for an explanation of the network scripts.

The `ifup` script is a generic script which does a few things and then calls interface-specific scripts like `ifup-ethX`, `ifup-wireless`, `ifup-ppp`, and so on. When a user runs **ifup eth0** manually, the following occurs:

1. `ifup` looks for a file called `/etc/sysconfig/network-scripts/ifcfg-eth0`;

1. if the `ifcfg` file exists, `ifup` looks for the `TYPE` key in that file to determine which type-specific script to call;

1. `ifup` calls `ifup-wireless` or `ifup-eth` or `ifup-XXX` based on `TYPE`;

1. the type-specific scripts do type-specific setup;

1. and then the type-specific scripts let common functions perform `IP`-related tasks like `DHCP` or static setup.

On bootup, `/etc/init.d/network` reads through all the `ifcfg` files and for each one that has **ONBOOT=yes**, it checks whether NetworkManager is already starting the DEVICE from that `ifcfg` file. If NetworkManager is starting that device or has already started it, nothing more is done for that file, and the next **ONBOOT=yes** file is checked. If NetworkManager is not yet starting that device, the initscripts will continue with their traditional behavior and call `ifup` for that `ifcfg` file.

The end result is that any `ifcfg` file that has **ONBOOT=yes** is expected to be started on system bootup, either by NetworkManager or by the initscripts. This ensures that some legacy network types which NetworkManager does not handle (such as ISDN or analog dialup modems) as well as any new application not yet supported by NetworkManager are still correctly started by the initscripts even though NetworkManager is unable to handle them.

### Note

It is recommended not to store backup `ifcfg` files in the same location as the live ones. The script literally does **ifcfg-\*** with an exclude only for these extensions: `.old`, `.orig`, `.rpmnew`, `.rpmorig`, and `.rpmsave`. The best way is not to store backup files anywhere within the `/etc/` directory.

## 1\.8. Additional Resources	{#sec-Introduction_to_Fedora_Networking-additional_resources}

The following sources of information provide additional resources regarding networking for Fedora.

### 1\.8.1. Installed Documentation	{#sec-Introduction_to_Fedora_Networking-docs-inst}

* `man(1)` man page — Describes man pages and how to find them.

* `NetworkManager(8)` man page — Describes the network management daemon.

* `NetworkManager.conf(5)` man page — Describes the `NetworkManager` configuration file.

* ``/usr/share/doc/initscripts-_`version`_/sysconfig.txt`` — Describes configuration files and their directives.

## Chapter 2. Configure Networking	{#ch-Configure_Networking}

## 2\.1. Static and Dynamic Interface Settings	{#sec-Static_and_Dynamic_Interface_Settings}

When to use static addressing and when to use dynamic addressing? These decisions are subjective, they depend on your accessed needs, your specific requirements. Having a policy, documenting it, and applying it consistently are usually more important than the specific decisions you make. In a traditional company LAN, this is an easier decision to make as you typically have fewer servers than other hosts. Provisioning and installation tools make providing static configurations to new hosts easy and using such tools will change your work flow and requirements. The following two sections are intended to provide guidance to those who have not already been through this decision-making process. For more information on automated configuration and management, see the OpenLMI section in the _System Administrators Guide_. The _System Installation Guide_ documents the use of kickstart which can also be used for automating the assignment of network settings.

### 2\.1.1. When to Use Static Network Interface Settings	{#sec-When_to_Use_Static_Network_Interface_Settings}

Use static `IP` addressing on those servers and devices whose network availability you want to ensure when automatic assignment methods, such as `DHCP`, fail. `DHCP`, `DNS`, and authentication servers are typical examples. Interfaces for out-of-band management devices are also worth configuring with static settings as these devices are supposed to work, as far as is possible, independently of other network infrastructure.

For hosts which are not considered vital, but for which static `IP` addressing is still considered desirable, use an automated provisioning method when possible. For example, `DHCP` servers can be configured to provide the same `IP` address to the same host every time. This method could be used for communal printers for example.

All the configuration tools listed in [Section 2.1.3, “Selecting Network Configuration Methods”](#sec-Selecting_Network_Configuration_Methods "2.1.3. Selecting Network Configuration Methods") allow assigning static `IP` addresses manually. The nmcli tool is also suitable for use with scripted assignment of network configuration.

### 2\.1.2. When to Use Dynamic Interface Settings	{#sec-When_to_Use_Dynamic_Interface_Settings}

Enable and use dynamic assignment of `IP` addresses and other network information whenever there is no compelling reason not to. The time saved in planning and documenting manual settings can be better spent elsewhere. The _dynamic host control protocol_ (DHCP) is a traditional method of dynamically assigning network configurations to hosts. See [Section 9.1, “Why Use DHCP?”](#sec-dhcp-why "9.1. Why Use DHCP?") for more information on this subject.

Note that NetworkManager will start the `DHCP` client, dhclient, automatically.

### 2\.1.3. Selecting Network Configuration Methods	{#sec-Selecting_Network_Configuration_Methods}

* To configure a network using graphical user interface tools, proceed to [Section 2.2, “Using NetworkManager with the GNOME Graphical User Interface”](#sec-Using_NetworkManager_with_the_GNOME_Graphical_User_Interface "2.2. Using NetworkManager with the GNOME Graphical User Interface")

* To configure a network interface manually, see [Section 2.3, “Using the Command Line Interface (CLI)”](#sec-Using_the_Command_Line_Interface "2.3. Using the Command Line Interface (CLI)").

* To configure an interface using NetworkManager's command-line tool, nmcli, proceed to [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli")

## 2\.2. Using NetworkManager with the GNOME Graphical User Interface	{#sec-Using_NetworkManager_with_the_GNOME_Graphical_User_Interface}

As of Fedora 20, NetworkManager does not have its own graphical user interface (GUI). The Network settings configuration tool is provided as part of the new GNOME control-center GUI. The old nm-connection-editor GUI is still available for certain tasks.

### 2\.2.1. Connecting to a Network Using a GUI	{#sec-Connecting_to_a_Network_Using_a_GUI}

Access the Network settings window of the control-center application as follow:

* Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears. Proceed to [Section 2.2.2, “Configuring New and Editing Existing Connections”](#sec-Configuring_New_and_Editing_Existing_Connections "2.2.2. Configuring New and Editing Existing Connections")

### 2\.2.2. Configuring New and Editing Existing Connections	{#sec-Configuring_New_and_Editing_Existing_Connections}

The Network settings window shows the connection status, its type and interface, its `IP` address and routing details, and so on.

Figure 2.1. Configure Networks Using the Network Settings Window

![Configure Networks Using the Network Settings Window][1]

<br />
[[D](ld-mediaobj-Network-Wired_Gnome3.png.html)]

<br />

The Network settings window has a menu on the left-hand side showing the available network devices or interfaces. This includes software interfaces such as for VLANs, bridges, bonds, and teams. On the right-hand side, the _connection profiles_ are shown for the selected network device or interface. A profile is a named collection of settings that can be applied to an interface. Below that is a plus and a minus button for adding and deleting new network connections, and on the right a gear wheel icon will appear for editing the connection details of the selected network device or VPN connection. To add a new connection, click the plus symbol to open the Add Network Connection window and proceed to [Section 2.2.2, “Configuring a New Connection”](#bh-Configuring_a_New_Connection "2.2.2. Configuring a New Connection").

#### Editing an Existing Connection	{#bh-Editing_an_Existing_Connection}

Clicking on the gear wheel icon of an existing connection profile in the Network settings window opens the Network details window, from where you can perform most network configuration tasks such as `IP` addressing, `DNS`, and routing configuration.

Figure 2.2. Configure Networks Using the Network Connection Details Window

![Configure Networks Using the Network Connection Details Window][2]

<br />
[[D](ld-mediaobj-Network-Details-Wired_Gnome3.png.html)]

<br />

#### Configuring a New Connection	{#bh-Configuring_a_New_Connection}

In the Network settings window, click the plus sign below the menu to open the Add Network Connection window. This displays a list of connection types that can be added.

Then, to configure:

* VPN connections, click the VPN entry and proceed to [Section 2.2.7, “Establishing a VPN Connection”](#sec-Establishing_a_VPN_Connection "2.2.7. Establishing a VPN Connection");

* Bond connections, click the Bond entry and proceed to [Section 4.2.1, “Establishing a Bond Connection”](#sec-Establishing_a_Bond_Connection "4.2.1. Establishing a Bond Connection");

* Bridge connections, click the Bridge entry and proceed to [Section 6.1.1, “Establishing a Bridge Connection”](#sec-Establishing_a_Bridge_Connection "6.1.1. Establishing a Bridge Connection");

* VLAN connections, click the VLAN entry and proceed to [Section 7.1.1, “Establishing a VLAN Connection”](#sec-Establishing_a_VLAN_Connection "7.1.1. Establishing a VLAN Connection");or,

* Team connections, click the Team entry and proceed to [Section 5.9, “Creating a Network Team Using a GUI”](#sec-Creating_a_Network_Team_Using_a_GUI "5.9. Creating a Network Team Using a GUI").

### 2\.2.3. Connecting to a Network Automatically	{#sec-Connecting_to_a_Network_Automatically}

For any connection type you add or configure, you can choose whether you want NetworkManager to try to connect to that network automatically when it is available.

Procedure 2.1. Configuring NetworkManager to Connect to a Network Automatically When Detected

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the network interface from the left-hand-side menu.

1. Click on the gear wheel icon of a connection profile on the right-hand side menu. If you have only one profile associated with the selected interface the gear wheel icon will be in the lower right-hand-side corner. The Network details window appears.

1. Select the Identity menu entry on the left. The Network window changes to the identity view.

1. Select Connect automatically to cause NetworkManager to auto-connect to the connection whenever NetworkManager detects that it is available. Clear the check box if you do not want NetworkManager to connect automatically. If the check box is clear, you will have to select that connection manually in the network applet menu to cause it to connect.

### 2\.2.4. System-wide and Private Connection Profiles	{#sec-System-wide_and_Private_Connection_Profiles}

NetworkManager stores all _connection profiles_. A profile is a named collection of settings that can be applied to an interface. NetworkManager stores these connection profiles for system-wide use (_system connections_), as well as all _user connection_ profiles. Access to the connection profiles is controlled by permissions which are stored by NetworkManager. See the `nm-settings(5)` man page for more information on the `connection` settings `permissions` property. The permissions correspond to the **USERS** directive in the `ifcfg` files. If the **USERS** directive is not present, the network profile will be available to all users. As an example, the following command in an `ifcfg` file will make the connection available only to the users listed:

	USERS="joe bob alice"

This can also be set using graphical user interface tools. In nm-connection-editor, there is the corresponding All users may connect to this network check box on the General tab, and in the GNOME control-center Network settings Identity window, there is the Make available to other users check box.

NetworkManager's default policy is to allow all users to create and modify system-wide connections. Profiles that should be available at boot time cannot be private because they will not be visible until the user logs in. For example, if user `user` creates a connection profile `user-em2` with the Connect Automatically check box selected but with the Make available to other users not selected, then the connection will not be available at boot time.

To restrict connections and networking, there are two options which can be used alone or in combination:

* Clear the Make available to other users check box, which changes the connection to be modifiable and usable only by the user doing the changing.

* Use the polkit framework to restrict permissions of general network operations on a per-user basis.

The combination of these two options provides fine-grained security and control over networking. See the `polkit(8)` man page for more information on polkit.

Note that VPN connections are **always** created as private-per-user, since they are assumed to be more private than a Wi-Fi or Ethernet connection.

Procedure 2.2. Changing a Connection to Be User-specific Instead of System-Wide, or Vice Versa

Depending on the system's policy, you may need root privileges on the system in order to change whether a connection is user-specific or system-wide.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the network interface from the left-hand-side menu.

1. Click on the gear wheel icon of a connection profile on the right-hand side menu. If you have only one profile associated with the selected interface the gear wheel icon will be in the lower right-hand-side corner. The Network details window appears.

1. Select the Identity menu entry on the left. The Network window changes to the identity view.

1. Select the Make available to other users check box to cause NetworkManager to make the connection available system-wide. Depending on system policy, you may then be prompted for the root password by the PolicyKit application. If so, enter the `root` password to finalize the change.

    Conversely, clear the Make available to other users check box to make the connection user-specific.

### 2\.2.5. Configuring a Wired (Ethernet) Connection	{#sec-Configuring_a_Wired_Ethernet_Connection}

To configure a wired network connection, press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

Select the Wired network interface from the left-hand-side menu if it is not already highlighted.

The system creates and configures a single wired _connection profile_ called Wired by default. A profile is a named collection of settings that can be applied to an interface. More than one profile can be created for an interface and applied as needed. The default profile cannot be deleted but its settings can be changed. You can edit the default Wired profile by clicking the gear wheel icon. You can create a new wired connection profile by clicking the Add Profile button. Connection profiles associated with a selected interface are shown on the right-hand side menu.

When you add a new connection by clicking the Add Profile button, NetworkManager creates a new configuration file for that connection and then opens the same dialog that is used for editing an existing connection. The difference between these dialogs is that an existing connection profile has a Details and Reset menu entry. In effect, you are always editing a connection profile; the difference only lies in whether that connection previously existed or was just created by NetworkManager when you clicked Add Profile.

#### Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings	{#bh-Configuring_the_Connection_Name_Auto-Connect_Behavior_and_Availability_Settings-wired}

Many settings in the Editing dialog are common to all connection types, see the Identity view if using the GNOME tool or the General tab if using nm-connection-editor:

* Name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

* MAC Address — Select the MAC address of the interface this profile must be applied to.

* Cloned Address — If required, enter a different MAC address to use.

* MTU — If required, enter a specific _maximum transmission unit_ (MTU) to use. The MTU value represents the size in bytes of the largest packet that the link-layer will transmit. This value defaults to `1500` and does not generally need to be specified or changed.

* Firewall Zone — If required, select a different firewall zone to apply. See the _[Red Hat Enterprise Linux 7 Security Guide](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Security_Guide/)_ for more information on firewall zones.

* Connect Automatically — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

* Make available to other users — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

* Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to the selected VPN connection when this connection profile is connected. Select the VPN from the drop-down menu.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-Wired}

Once you have finished editing your wired connection, click the Apply button to save your customized configuration. If the profile was in use while being edited, power cycle the connection to make NetworkManager apply the changes. If the profile is OFF, set it to ON. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking the gear wheel icon to return to the editing dialog.

Then, to configure:

* port-based Network Access Control (PNAC), click the 802\.1X Security tab and proceed to [Section 2.2.10.1, “Configuring 802.1X Security”](#sec-Configuring_802.1X_Security "2.2.10.1. Configuring 802.1X Security");

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"); or,

* `IPv6` settings for the connection, click the IPv6 Settings tab and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

### 2\.2.6. Configuring a Wi-Fi Connection	{#sec-Configuring_a_Wi-Fi_Connection}

This section explains how to use NetworkManager to configure a Wi-Fi (also known as wireless or 802.11_`a/b/g/n`_) connection to an Access Point.

To configure a mobile broadband (such as 3G) connection, see [Section 2.2.8, “Establishing a Mobile Broadband Connection”](#sec-Establishing_a_Mobile_Broadband_Connection "2.2.8. Establishing a Mobile Broadband Connection").

#### Quickly Connecting to an Available Access Point	{#bh-Quickly_Connecting_to_an_Available_Access_Point}

The easiest way to connect to an available access point is to click on the network connection icon to activate the Notification Area applet, locate the _Service Set Identifier_ (SSID) of the access point in the list of Wi-Fi networks, and click on it. A padlock symbol indicates the access point requires authentication. If the access point is secured, a dialog prompts you for an authentication key or password.

NetworkManager tries to auto-detect the type of security used by the access point. If there are multiple possibilities, NetworkManager guesses the security type and presents it in the Wi-Fi security drop-down menu. To see if there are multiple choices, click the Wi-Fi security drop-down menu and select the type of security the access point is using. If you are unsure, try connecting to each type in turn. Finally, enter the key or passphrase in the Password field. Certain password types, such as a 40-bit WEP or 128-bit WPA key, are invalid unless they are of a requisite length. The Connect button will remain inactive until you enter a key of the length required for the selected security type. To learn more about wireless security, see [Section 2.2.10.2, “Configuring Wi-Fi Security”](#sec-Configuring_Wi-Fi_Security "2.2.10.2. Configuring Wi-Fi Security").

If NetworkManager connects to the access point successfully, the Notification Area applet icon will change into a graphical indicator of the wireless connection's signal strength.

You can also edit the settings for one of these auto-created access point connections just as if you had added it yourself. The Wi-Fi page of the Network window has a History button. Clicking this reveals a list of all the connections you have ever tried to connect to. See [Section 2.2.6, “Editing a Connection, or Creating a Completely New One”](#bh-Editing_a_Connection_or_Creating_a_Completely_New_One "2.2.6. Editing a Connection, or Creating a Completely New One")

#### Connecting to a Hidden Wi-Fi Network	{#bh-Connecting_to_a_Hidden_Wi-Fi_Network}

All access points have a _Service Set Identifier_ (SSID) to identify them. However, an access point may be configured not to broadcast its SSID, in which case it is _hidden_, and will not show up in NetworkManager's list of Available networks. You can still connect to a wireless access point that is hiding its SSID as long as you know its SSID, authentication method, and secrets.

To connect to a hidden wireless network, press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network window appears. Select Wi-Fi from the menu and then select Connect to Hidden Network to cause a dialog to appear. If you have connected to the hidden network before, use the Connection dropdown to select it, and click Connect. If you have not, leave the Connection dropdown as New, enter the SSID of the hidden network, select its Wi-Fi security method, enter the correct authentication secrets, and click Connect.

For more information on wireless security settings, see [Section 2.2.10.2, “Configuring Wi-Fi Security”](#sec-Configuring_Wi-Fi_Security "2.2.10.2. Configuring Wi-Fi Security").

#### Editing a Connection, or Creating a Completely New One	{#bh-Editing_a_Connection_or_Creating_a_Completely_New_One}

You can edit an existing connection that you have tried or succeeded in connecting to in the past by opening the Wi-Fi page of the Network dialog and selecting the gear wheel icon to the right of the Wi-Fi connection name. If the network is not currently in range, click History to display past connections. When you click the gear wheel icon the editing connection dialog appears. The Details window shows the connection details.

To configure a new connection whose SSID is in range, first attempt to connect to it by opening the Network window, selecting the Wi-Fi menu entry, and clicking the connection name (by default, the same as the SSID). If the SSID is not in range, see [Section 2.2.6, “Connecting to a Hidden Wi-Fi Network”](#bh-Connecting_to_a_Hidden_Wi-Fi_Network "2.2.6. Connecting to a Hidden Wi-Fi Network"). If the SSID is in range, the procedure is as follows:

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the Wi-Fi menu entry.

1. Click the Wi-Fi connection profile on the right-hand side menu you want to connect to. A padlock symbol indicates a key or password is required.

1. If requested, enter the authentication details.

#### Configuring the SSID, Auto-Connect Behavior, and Availability Settings	{#bh-Configuring_the_SSID-Connect_Behavior_and_Availability_Settings-wireless}

To edit a Wi-Fi connection's settings, select Wi-Fi in the Network page and then select the gear wheel icon to the right of the Wi-Fi connection name. Select Identity. The following settings are available:

SSID
:    The _Service Set Identifier_ (SSID) of the access point (AP).

BSSID
:    The _Basic Service Set Identifier_ (BSSID) is the MAC address, also known as a _hardware address_, of the specific wireless access point you are connecting to when in Infrastructure mode. This field is blank by default, and you are able to connect to a wireless access point by SSID without having to specify its BSSID. If the BSSID is specified, it will force the system to associate to a specific access point only.

For ad-hoc networks, the BSSID is generated randomly by the mac80211 subsystem when the ad-hoc network is created. It is not displayed by NetworkManager

MAC address
:    Like an Ethernet Network Interface Card (NIC), a wireless adapter has a unique MAC address (Media Access Control; also known as a _hardware address_) that identifies it to the system. Running the **ip addr** command will show the MAC address associated with each interface. For example, in the following **ip addr** output, the MAC address for the `wlan0` interface (which is `00:1c:bf:02:f8:70`) immediately follows the `link/ether` keyword:

	~]# **ip addr**
	1: lo: &lt;LOOPBACK,UP,LOWER_UP&gt; mtu 16436 qdisc noqueue state UNKNOWN
	    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
	    inet 127.0.0.1/8 scope host lo
	    inet6 ::1/128 scope host
	       valid_lft forever preferred_lft forever
	2: eth0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
	    link/ether 52:54:00:26:9e:f1 brd ff:ff:ff:ff:ff:ff
	    inet 192.168.122.251/24 brd 192.168.122.255 scope global eth0
	    inet6 fe80::5054:ff:fe26:9ef1/64 scope link
	       valid_lft forever preferred_lft forever
	3: wlan0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc mq state UP qlen 1000
	    link/ether _00:1c:bf:02:f8:70_ brd ff:ff:ff:ff:ff:ff
	    inet 10.200.130.67/24 brd 10.200.130.255 scope global wlan0
	    inet6 fe80::21c:bfff:fe02:f870/64 scope link
	       valid_lft forever preferred_lft forever

A single system could have one or more wireless network adapters connected to it. The MAC address field therefore allows you to associate a specific wireless adapter with a specific connection (or connections). As mentioned, you can determine the MAC address using the **ip addr** command, and then copy and paste that value into the MAC address text-entry field.

Cloned Address
:    A cloned MAC address to use in place of the real hardware address.

The following settings are common to all connection profiles:

* Connect automatically — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

* Make available to other users — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-wireless}

Once you have finished editing the wireless connection, click the Apply button to save your configuration. Given a correct configuration, you can connect to your modified connection by selecting it from the Notification Area applet. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for details on selecting and connecting to a network.

You can further configure an existing connection by selecting it in the Network window and clicking the gear wheel icon to reveal the connection details.

Then, to configure:

* security authentication for the wireless connection, click Security and proceed to [Section 2.2.10.2, “Configuring Wi-Fi Security”](#sec-Configuring_Wi-Fi_Security "2.2.10.2. Configuring Wi-Fi Security");

* `IPv4` settings for the connection, click IPv4 and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"); or,

* `IPv6` settings for the connection, click IPv6 and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

### 2\.2.7. Establishing a VPN Connection	{#sec-Establishing_a_VPN_Connection}

Establishing a Virtual Private Network (VPN) enables communication between your Local Area Network (LAN), and another, remote LAN. This is done by setting up a tunnel across an intermediate network such as the Internet. The VPN tunnel that is set up typically uses authentication and encryption. After successfully establishing a VPN connection using a secure tunnel, a VPN router or gateway performs the following actions upon the packets you transmit:

1. it adds an _Authentication Header_ for routing and authentication purposes;

1. it encrypts the packet data; and,

1. it encloses the data in packets according to the Encapsulating Security Payload (ESP) protocol, which constitutes the decryption and handling instructions.

The receiving VPN router strips the header information, decrypts the data, and routes it to its intended destination (either a workstation or other node on a network). Using a network-to-network connection, the receiving node on the local network receives the packets already decrypted and ready for processing. The encryption and decryption process in a network-to-network VPN connection is therefore transparent to clients.

Because they employ several layers of authentication and encryption, VPNs are a secure and effective means of connecting multiple remote nodes to act as a unified intranet.

Procedure 2.3. Adding a New VPN Connection

You can configure a new VPN connection by opening the Network window and selecting the plus symbol below the menu.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the plus symbol below the menu. The Add Network Connection window appears.

1. Select the VPN menu entry. The view now changes to offer configuring a VPN manually, or importing a VPN configuration file.

    The appropriate NetworkManager VPN plug-in for the VPN type you want to configure must be installed. (see _Fedora 20 System Administrator's Guide_ for more information on how to install new packages in Fedora 20).

1. Click the Add button to open the Choose a VPN Connection Type assistant.

1. Select the VPN protocol for the gateway you are connecting to from the menu. The VPN protocols available for selection in the menu correspond to the NetworkManager VPN plug-ins installed. For example, if the NetworkManager-openswan-gnome package is installed then the IPsec based VPN will be selectable from the menu.

1. The Add Network Connection window changes to present the settings customized for the type of VPN connection you selected in the previous step.

Procedure 2.4. Editing an Existing VPN Connection

You can configure an existing VPN connection by opening the Network window and selecting the name of the connection from the list. Then click the Edit button.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the VPN connection you wish to edit from the left hand menu.

1. Click the Configure button.

#### Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings	{#bh-Configuring_the_Connection_Name_Auto-Connect_Behavior_and_Availability_Settings-vpn}

Five settings in the Editing dialog are common to all connection types, see the General tab:

* Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

* Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

* All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

* Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the dropdown menu.

* Firewall Zone — Select the Firewall Zone from the dropdown menu.

#### Configuring the VPN Tab	{#bh-Configuring_the_VPN_Tab}

Gateway
:    The name or `IP` address of the remote VPN gateway.

Group name
:    The name of a VPN group configured on the remote gateway.

User password
:    If required, enter the password used to authenticate with the VPN.

Group password
:    If required, enter the password used to authenticate with the VPN.

User name
:    If required, enter the user name used to authenticate with the VPN.

Phase1 Algorithms
:    If required, enter the algorithms to be used to authenticate and set up an encrypted channel.

Phase2 Algorithms
:    If required, enter the algorithms to be used for the IPsec negotiations.

Domain
:    If required, enter the Domain Name.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-vpn}

Once you have finished editing your new VPN connection, click the Save button to save your customized configuration. If the profile was in use while being edited, power cycle the connection to make NetworkManager apply the changes. If the profile is OFF, set it to ON. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking Configure to return to the Editing dialog.

Then, to configure:

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings").

### 2\.2.8. Establishing a Mobile Broadband Connection	{#sec-Establishing_a_Mobile_Broadband_Connection}

You can use NetworkManager's mobile broadband connection abilities to connect to the following _2G_ and _3G_ services:

* 2G — _GPRS_ (_General Packet Radio Service_), _EDGE_ (_Enhanced Data Rates for GSM Evolution_), or CDMA (Code Division Multiple Access).

* 3G — _UMTS_ (_Universal Mobile Telecommunications System_), _HSPA_ (_High Speed Packet Access_), or EVDO (EVolution Data-Only).

Your computer must have a mobile broadband device (modem), which the system has discovered and recognized, in order to create the connection. Such a device may be built into your computer (as is the case on many notebooks and netbooks), or may be provided separately as internal or external hardware. Examples include PC card, USB Modem or Dongle, mobile or cellular telephone capable of acting as a modem.

Procedure 2.5. Adding a New Mobile Broadband Connection

You can configure a mobile broadband connection by opening the Network Connections tool and selecting the Mobile Broadband tab.

1. Press the **Super** key to enter the Activities Overview, type **nm-connection-editor** and then press **Enter**. The Network Connections tool appears.

1. Click the Add button. The Choose a Connection Type menu opens.

1. Select the Mobile Broadband menu entry.

1. Click Create to open the Set up a Mobile Broadband Connection assistant.

1. Under Create a connection for this mobile broadband device, choose the 2G- or 3G-capable device you want to use with the connection. If the drop-down menu is inactive, this indicates that the system was unable to detect a device capable of mobile broadband. In this case, click Cancel, ensure that you do have a mobile broadband-capable device attached and recognized by the computer and then retry this procedure. Click the Continue button.

1. Select the country where your service provider is located from the list and click the Continue button.

1. Select your provider from the list or enter it manually. Click the Continue button.

1. Select your payment plan from the drop-down menu and confirm the _Access Point Name_ (APN) is correct. Click the Continue button.

1. Review and confirm the settings and then click the Apply button.

1. Edit the mobile broadband-specific settings by referring to [Section 2.2.8, “Configuring the Mobile Broadband Tab”](#bh-Configuring_the_Mobile_Broadband_Tab "2.2.8. Configuring the Mobile Broadband Tab").

Procedure 2.6. Editing an Existing Mobile Broadband Connection

Follow these steps to edit an existing mobile broadband connection.

1. Press the **Super** key to enter the Activities Overview, type **nm-connection-editor** and then press **Enter**. The Network Connections tool appears.

1. Select the Mobile Broadband tab.

1. Select the connection you wish to edit and click the Edit button.

1. Configure the connection name, auto-connect behavior, and availability settings.

    Five settings in the Editing dialog are common to all connection types, see the General tab:

  * Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

  * Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

  * All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

  * Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the dropdown menu.

  * Firewall Zone — Select the Firewall Zone from the drop-down menu.

1. Edit the mobile broadband-specific settings by referring to [Section 2.2.8, “Configuring the Mobile Broadband Tab”](#bh-Configuring_the_Mobile_Broadband_Tab "2.2.8. Configuring the Mobile Broadband Tab").

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-mobile_broadband}

Once you have finished editing your mobile broadband connection, click the Apply button to save your customized configuration. If the profile was in use while being edited, power cycle the connection to make NetworkManager apply the changes. If the profile is OFF, set it to ON. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network Connections window and clicking Edit to return to the Editing dialog.

Then, to configure:

* Point-to-point settings for the connection, click the PPP Settings tab and proceed to [Section 2.2.10.3, “Configuring PPP (Point-to-Point) Settings”](#sec-Configuring_PPP_Point-to-Point_Settings "2.2.10.3. Configuring PPP (Point-to-Point) Settings");

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"); or,

* `IPv6` settings for the connection, click the IPv6 Settings tab and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

#### Configuring the Mobile Broadband Tab	{#bh-Configuring_the_Mobile_Broadband_Tab}

If you have already added a new mobile broadband connection using the assistant (see [Procedure 2.5, “Adding a New Mobile Broadband Connection”](#procedure-Adding_a_New_Mobile_Broadband_Connection "Procedure 2.5. Adding a New Mobile Broadband Connection") for instructions), you can edit the Mobile Broadband tab to disable roaming if home network is not available, assign a network ID, or instruct NetworkManager to prefer a certain technology (such as 3G or 2G) when using the connection.

Number
:    The number that is dialed to establish a PPP connection with the GSM-based mobile broadband network. This field may be automatically populated during the initial installation of the broadband device. You can usually leave this field blank and enter the APN instead.

Username
:    Enter the user name used to authenticate with the network. Some providers do not provide a user name, or accept any user name when connecting to the network.

Password
:    Enter the password used to authenticate with the network. Some providers do not provide a password, or accept any password.

APN
:    Enter the _Access Point Name_ (APN) used to establish a connection with the GSM-based network. Entering the correct APN for a connection is important because it often determines:

* how the user is billed for their network usage; and/or

* whether the user has access to the Internet, an intranet, or a subnetwork.

Network ID
:    Entering a Network ID causes NetworkManager to force the device to register only to a specific network. This can be used to ensure the connection does not roam when it is not possible to control roaming directly.

Type
:    Any — The default value of Any leaves the modem to select the fastest network.

3G (UMTS/HSPA) — Force the connection to use only 3G network technologies.

2G (GPRS/EDGE) — Force the connection to use only 2G network technologies.

Prefer 3G (UMTS/HSPA) — First attempt to connect using a 3G technology such as HSPA or UMTS, and fall back to GPRS or EDGE only upon failure.

Prefer 2G (GPRS/EDGE) — First attempt to connect using a 2G technology such as GPRS or EDGE, and fall back to HSPA or UMTS only upon failure.

Allow roaming if home network is not available
:    Uncheck this box if you want NetworkManager to terminate the connection rather than transition from the home network to a roaming one, thereby avoiding possible roaming charges. If the box is checked, NetworkManager will attempt to maintain a good connection by transitioning from the home network to a roaming one, and vice versa.

PIN
:    If your device's _SIM_ (_Subscriber Identity Module_) is locked with a _PIN_ (_Personal Identification Number_), enter the PIN so that NetworkManager can unlock the device. NetworkManager must unlock the SIM if a PIN is required in order to use the device for any purpose.

### 2\.2.9. Establishing a DSL Connection	{#sec-Establishing_a_DSL_Connection}

This section is intended for those installations which have a DSL card fitted within a host rather than the external combined DSL modem router combinations typical of private consumer or SOHO installations.

Procedure 2.7. Adding a New DSL Connection

You can configure a new DSL connection by opening the Network Connections window, clicking the Add button and selecting DSL from the Hardware section of the new connection list.

1. Press the **Super** key to enter the Activities Overview, type **nm-connection-editor** and then press **Enter**. The Network Connections tool appears.

1. Click the Add button.

1. The Choose a Connection Type list appears.

1. Select DSL and press the Create button.

1. The Editing DSL Connection _`1`_ window appears.

Procedure 2.8. Editing an Existing DSL Connection

You can configure an existing DSL connection by opening the Network Connections window and selecting the name of the connection from the list. Then click the Edit button.

1. Press the **Super** key to enter the Activities Overview, type **nm-connection-editor** and then press **Enter**. The Network Connections tool appears.

1. Select the connection you wish to edit and click the Edit button.

#### Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings	{#bh-Configuring_the_Connection_Name_Auto-Connect_Behavior_and_Availability_Settings-dsl}

Five settings in the Editing dialog are common to all connection types, see the General tab:

* Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

* Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

* All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

* Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the dropdown menu.

* Firewall Zone — Select the Firewall Zone from the drop-down menu.

#### Configuring the DSL Tab	{#bh-Configuring_the_DSL_Tab}

Username
:    Enter the user name used to authenticate with the service provider.

Service
:    Leave blank unless otherwise directed by your service provider.

Password
:    Enter the password supplied by the service provider.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-DSL}

Once you have finished editing your DSL connection, click the Apply button to save your customized configuration. If the profile was in use while being edited, power cycle the connection to make NetworkManager apply the changes. If the profile is OFF, set it to ON. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network Connections window and clicking Edit to return to the Editing dialog.

Then, to configure:

* The MAC address and MTU settings, click the Wired tab and proceed to [Section 2.2.5, “Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings”](#bh-Configuring_the_Connection_Name_Auto-Connect_Behavior_and_Availability_Settings-wired "2.2.5. Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings");

* Point-to-point settings for the connection, click the PPP Settings tab and proceed to [Section 2.2.10.3, “Configuring PPP (Point-to-Point) Settings”](#sec-Configuring_PPP_Point-to-Point_Settings "2.2.10.3. Configuring PPP (Point-to-Point) Settings");

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings").

### 2\.2.10. Configuring Connection Settings	{#sec-Configuring_Connection_Settings}

#### 2\.2.10.1. Configuring 802.1X Security	{#sec-Configuring_802.1X_Security}

802.1X security is the name of the IEEE standard for _port-based Network Access Control_ (PNAC). It is also called _WPA Enterprise_. Simply put, 802.1X security is a way of controlling access to a _logical network_ from a physical one. All clients who want to join the logical network must authenticate with the server (a router, for example) using the correct 802.1X authentication method.

802.1X security is most often associated with securing wireless networks (WLANs), but can also be used to prevent intruders with physical access to the network (LAN) from gaining entry. In the past, `DHCP` servers were configured not to lease `IP` addresses to unauthorized users, but for various reasons this practice is both impractical and insecure, and thus is no longer recommended. Instead, 802.1X security is used to ensure a logically-secure network through port-based authentication.

802.1X provides a framework for WLAN and LAN access control and serves as an envelope for carrying one of the Extensible Authentication Protocol (EAP) types. An EAP type is a protocol that defines how security is achieved on the network.

You can configure 802.1X security for a wired or wireless connection type by opening the Network window (see [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI")) and following the applicable procedure below. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears. Proceed to [Procedure 2.9, “For a Wired Connection”](#procedure-For_a_Wired_Connection "Procedure 2.9. For a Wired Connection") or [Procedure 2.10, “For a Wireless Connection”](#procedure-For_a_Wireless_Connection "Procedure 2.10. For a Wireless Connection"):

Procedure 2.9. For a Wired Connection

1. Select a Wired network interface from the left-hand-side menu.

1. Either click on Add Profile to add a new network connection profile for which you want to configure 802.1X security, or select an existing connection profile and click the gear wheel icon.

1. Then select Security and set the symbolic power button to ON to enable settings configuration.

1. Proceed to [Section 2.2.10.1.1, “Configuring TLS (Transport Layer Security) Settings”](#sec-Configuring_TLS_Transport_Layer_Security_Settings "2.2.10.1.1. Configuring TLS (Transport Layer Security) Settings")

Procedure 2.10. For a Wireless Connection

1. Select a Wireless network interface from the left-hand-side menu. If necessary, set the symbolic power button to ON and check that your hardware switch is on.

1. Either select the connection name of a new connection, or click the gear wheel icon of an existing connection profile, for which you want to configure 802.1X security. In the case of a new connection, complete any authentication steps to complete the connection and then click the gear wheel icon.

1. Select Security.

1. From the drop-down menu select one of the following security methods: LEAP, Dynamic WEP (802.1X), or WPA &amp; WPA2 Enterprise.

1. Refer to [Section 2.2.10.1.1, “Configuring TLS (Transport Layer Security) Settings”](#sec-Configuring_TLS_Transport_Layer_Security_Settings "2.2.10.1.1. Configuring TLS (Transport Layer Security) Settings") for descriptions of which _extensible authentication protocol_ (EAP) types correspond to your selection in the Security drop-down menu.

##### 2\.2.10.1.1. Configuring TLS (Transport Layer Security) Settings	{#sec-Configuring_TLS_Transport_Layer_Security_Settings}

With Transport Layer Security, the client and server mutually authenticate using the TLS protocol. The server demonstrates that it holds a digital certificate, the client proves its own identity using its client-side certificate, and key information is exchanged. Once authentication is complete, the TLS tunnel is no longer used. Instead, the client and server use the exchanged keys to encrypt data using AES, TKIP or WEP.

The fact that certificates must be distributed to all clients who want to authenticate means that the EAP-TLS authentication method is very strong, but also more complicated to set up. Using TLS security requires the overhead of a public key infrastructure (PKI) to manage certificates. The benefit of using TLS security is that a compromised password does not allow access to the (W)LAN: an intruder must also have access to the authenticating client's private key.

NetworkManager does not determine the version of TLS supported. NetworkManager gathers the parameters entered by the user and passes them to the daemon, wpa\_supplicant, that handles the procedure. It in turn uses OpenSSL to establish the TLS tunnel. OpenSSL itself negotiates the SSL/TLS protocol version. It uses the highest version both ends support.

###### Selecting an Authentication Method	{#Selecting_an_Authentication_Method}

Select from one of following authentication methods:

* Select TLS for _Transport Layer Security_ and proceed to [Section 2.2.10.1.2, “Configuring TLS Settings”](#sec-Configuring_TLS_Settings "2.2.10.1.2. Configuring TLS Settings");

* Select FAST for _Flexible Authentication via Secure Tunneling_ and proceed to [Section 2.2.10.1.4, “Configuring Tunneled TLS Settings”](#sec-Configuring_Tunneled_TLS_Settings "2.2.10.1.4. Configuring Tunneled TLS Settings");

* Select Tunneled TLS for _Tunneled Transport Layer Security_, otherwise known as TTLS, or EAP-TTLS and proceed to [Section 2.2.10.1.4, “Configuring Tunneled TLS Settings”](#sec-Configuring_Tunneled_TLS_Settings "2.2.10.1.4. Configuring Tunneled TLS Settings");

* Select Protected EAP (PEAP) for _Protected Extensible Authentication Protocol_ and proceed to [Section 2.2.10.1.5, “Configuring Protected EAP (PEAP) Settings”](#sec-Configuring_Protected_EAP_PEAP_Settings "2.2.10.1.5. Configuring Protected EAP (PEAP) Settings").

##### 2\.2.10.1.2. Configuring TLS Settings	{#sec-Configuring_TLS_Settings}

Identity
:    Provide the identity of this server.

User certificate
:    Click to browse for, and select, a personal X.509 certificate file encoded with _Distinguished Encoding Rules_ (DER) or _Privacy Enhanced Mail_ (PEM).

CA certificate
:    Click to browse for, and select, an X.509 _certificate authority_ certificate file encoded with _Distinguished Encoding Rules_ (DER) or _Privacy Enhanced Mail_ (PEM).

Private key
:    Click to browse for, and select, a _private key_ file encoded with _Distinguished Encoding Rules_ (DER), _Privacy Enhanced Mail_ (PEM), or the _Personal Information Exchange Syntax Standard_ (PKCS #12).

Private key password
:    Enter the password for the private key in the Private key field. Select Show password to make the password visible as you type it.

##### 2\.2.10.1.3. Configuring FAST Settings	{#sec-Configuring_FAST_Settings}

Anonymous Identity
:    Provide the identity of this server.

PAC provisioning
:    Select the check box to enable and then select from Anonymous, Authenticated, and Both.

PAC file
:    Click to browse for, and select, a _protected access credential_ (PAC) file.

Inner authentication
:    GTC — Generic Token Card.

MSCHAPv2 — Microsoft Challenge Handshake Authentication Protocol version 2.

Username
:    Enter the user name to be used in the authentication process.

Password
:    Enter the password to be used in the authentication process.

##### 2\.2.10.1.4. Configuring Tunneled TLS Settings	{#sec-Configuring_Tunneled_TLS_Settings}

Anonymous identity
:    This value is used as the unencrypted identity.

CA certificate
:    Click to browse for, and select, a Certificate Authority's certificate.

Inner authentication
:    PAP — Password Authentication Protocol.

MSCHAP — Challenge Handshake Authentication Protocol.

MSCHAPv2 — Microsoft Challenge Handshake Authentication Protocol version 2.

CHAP — Challenge Handshake Authentication Protocol.

Username
:    Enter the user name to be used in the authentication process.

Password
:    Enter the password to be used in the authentication process.

##### 2\.2.10.1.5. Configuring Protected EAP (PEAP) Settings	{#sec-Configuring_Protected_EAP_PEAP_Settings}

Anonymous Identity
:    This value is used as the unencrypted identity.

CA certificate
:    Click to browse for, and select, a Certificate Authority's certificate.

PEAP version
:    The version of Protected EAP to use. Automatic, 0 or 1.

Inner authentication
:    MSCHAPv2 — Microsoft Challenge Handshake Authentication Protocol version 2.

MD5 — Message Digest 5, a cryptographic hash function.

GTC — Generic Token Card.

Username
:    Enter the user name to be used in the authentication process.

Password
:    Enter the password to be used in the authentication process.

#### 2\.2.10.2. Configuring Wi-Fi Security	{#sec-Configuring_Wi-Fi_Security}

Security
:    None — Do not encrypt the Wi-Fi connection.

WEP 40/128-bit Key — Wired Equivalent Privacy (WEP), from the IEEE 802.11 standard. Uses a single pre-shared key (PSK).

WEP 128-bit Passphrase — An MD5 hash of the passphrase will be used to derive a WEP key.

LEAP — Lightweight Extensible Authentication Protocol, from Cisco Systems.

Dynamic WEP (802.1X) — WEP keys are changed dynamically. Use with [Section 2.2.10.1.1, “Configuring TLS (Transport Layer Security) Settings”](#sec-Configuring_TLS_Transport_Layer_Security_Settings "2.2.10.1.1. Configuring TLS (Transport Layer Security) Settings")

WPA &amp; WPA2 Personal — Wi-Fi Protected Access (WPA), from the draft IEEE 802.11i standard. A replacement for WEP. Wi-Fi Protected Access II (WPA2), from the 802.11i-2004 standard. Personal mode uses a pre-shared key (WPA-PSK).

WPA &amp; WPA2 Enterprise — WPA for use with a RADIUS authentication server to provide IEEE 802.1X network access control. Use with [Section 2.2.10.1.1, “Configuring TLS (Transport Layer Security) Settings”](#sec-Configuring_TLS_Transport_Layer_Security_Settings "2.2.10.1.1. Configuring TLS (Transport Layer Security) Settings")

Password
:    Enter the password to be used in the authentication process.

#### 2\.2.10.3. Configuring PPP (Point-to-Point) Settings	{#sec-Configuring_PPP_Point-to-Point_Settings}

Configure Methods
:

Use point-to-point encryption (MPPE)
:    Microsoft Point-To-Point Encryption protocol ([_RFC 3078_](http://www.rfc-editor.org/info/rfc3078)).

Allow BSD data compression
:    PPP BSD Compression Protocol ([_RFC 1977_](http://www.rfc-editor.org/info/rfc1977)).

Allow Deflate data compression
:    PPP Deflate Protocol ([_RFC 1979_](http://www.rfc-editor.org/info/rfc1979)).

Use TCP header compression
:    Compressing TCP/IP Headers for Low-Speed Serial Links ([_RFC 1144_](http://www.rfc-editor.org/info/rfc1144)).

Send PPP echo packets
:    LCP Echo-Request and Echo-Reply Codes for loopback tests ([_RFC 1661_](http://www.rfc-editor.org/info/rfc1661)).

#### 2\.2.10.4. Configuring IPv4 Settings	{#sec-Configuring_IPv4_Settings}

The IPv4 Settings tab allows you to configure the method used to connect to a network, to enter `IP` address, route, and `DNS` information as required. The IPv4 Settings tab is available when you create and modify one of the following connection types: wired, wireless, mobile broadband, VPN or DSL. If you need to configure `IPv6` addresses, see [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings"). If you need to configure static routes, click the Routes button and proceed to [Section 2.2.10.6, “Configuring Routes”](#sec-Configuring_Routes "2.2.10.6. Configuring Routes").

If you are using `DHCP` to obtain a dynamic `IP` address from a `DHCP` server, you can simply set Method to Automatic (DHCP).

##### Setting the Method	{#bh-Setting_the_Method}

Available IPv4 Methods by Connection Type

When you click the Method drop-down menu, depending on the type of connection you are configuring, you are able to select one of the following `IPv4` connection methods. All of the methods are listed here according to which connection type, or types, they are associated with:

Method
:    Automatic (DHCP) — Choose this option if the network you are connecting to uses a `DHCP` server to assign `IP` addresses. You do not need to fill in the DHCP client ID field.

Automatic (DHCP) addresses only — Choose this option if the network you are connecting to uses a `DHCP` server to assign `IP` addresses but you want to assign `DNS` servers manually.

Link-Local Only — Choose this option if the network you are connecting to does not have a `DHCP` server and you do not want to assign `IP` addresses manually. Random addresses will be assigned as per [_RFC 3927_](http://www.rfc-editor.org/info/rfc3927) with prefix `169.254/16`.

Shared to other computers — Choose this option if the interface you are configuring is for sharing an Internet or WAN connection. The interface is assigned an address in the `10.42.x.1/24` range, a `DHCP` server and `DNS` server are started, and the interface is connected to the default network connection on the system with _network address translation_ (NAT).

Disabled — `IPv4` is disabled for this connection.

Wired, Wireless and DSL Connection Methods
:    Manual — Choose this option if you want to assign `IP` addresses manually.

Mobile Broadband Connection Methods
:    Automatic (PPP) — Choose this option if the network you are connecting to assigns your `IP` address and `DNS` servers automatically.

Automatic (PPP) addresses only — Choose this option if the network you are connecting to assigns your `IP` address automatically, but you want to manually specify `DNS` servers.

VPN Connection Methods
:    Automatic (VPN) — Choose this option if the network you are connecting to assigns your `IP` address and `DNS` servers automatically.

Automatic (VPN) addresses only — Choose this option if the network you are connecting to assigns your `IP` address automatically, but you want to manually specify `DNS` servers.

DSL Connection Methods
:    Automatic (PPPoE) — Choose this option if the network you are connecting to assigns your `IP` address and `DNS` servers automatically.

Automatic (PPPoE) addresses only — Choose this option if the network you are connecting to assigns your `IP` address automatically, but you wish to manually specify `DNS` servers.

For information on configuring static routes for the network connection, go to [Section 2.2.10.6, “Configuring Routes”](#sec-Configuring_Routes "2.2.10.6. Configuring Routes").

#### 2\.2.10.5. Configuring IPv6 Settings	{#sec-Configuring_IPv6_Settings}

Method
:    Ignore — Choose this option if you want to ignore `IPv6` settings for this connection.

Automatic — Choose this option to use _router advertisement_ (RA) to create an automatic, stateless configuration.

Automatic, addresses only — Choose this option if the network you are connecting to uses a `DHCP` server to assign `IP` addresses but you want to assign `DNS` servers manually.

Automatic, DHCP only — Choose this option to not use RA, but request information from DHCPv6 directly to create a stateful configuration.

Manual — Choose this option if the network you are connecting to does not have a `DHCP` server and you want to assign `IP` addresses manually.

Link-Local Only — Choose this option if the network you are connecting to does not have a `DHCP` server and you do not want to assign `IP` addresses manually. Random addresses will be assigned as per [_RFC 4862_](http://www.rfc-editor.org/info/rfc4862) with prefix `FE80::0`.

Addresses
:    DNS servers — Enter a comma separated list of `DNS` servers.

Search domains — Enter a comma separated list of domain controllers.

For information on configuring static routes for the network connection, go to [Section 2.2.10.6, “Configuring Routes”](#sec-Configuring_Routes "2.2.10.6. Configuring Routes").

#### 2\.2.10.6. Configuring Routes	{#sec-Configuring_Routes}

A host's routing table will be automatically populated with routes to directly connected networks. The routes are learned by examining the network interfaces when they are “up”. This section describes entering static routes to networks or hosts which can be reached by traversing an intermediate network or connection, such as a VPN tunnel or leased line. In order to reach a remote network or host, the system is given the address of a gateway to which traffic should be sent.

When a host's interface is configured by `DHCP`, an address of a gateway that leads to an upstream network or the Internet is usually assigned. This gateway is usually referred to as the default gateway as it is the gateway to use if no better route is known to the system (and present in the routing table). Network administrators often use the first or last host `IP` address in the network as the gateway address; for example, `192.168.10.1` or `192.168.10.254`. Not to be confused by the address which represents the network itself; in this example, `192.168.10.0`, or the subnet's broadcast address; in this example `192.168.10.255`.

##### Configuring Static Routes	{#Configuring_Static_Routes}

To set a static route, open the IPv4 or IPv6 settings window for the connection you want to configure. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for instructions on how to do that.

Routes
:    Address — Enter the `IP` address of a remote network, sub-net, or host.

Netmask — The netmask or prefix length of the `IP` address entered above.

Gateway — The `IP` address of the gateway leading to the remote network, sub-net, or host entered above.

Metric — A network cost, a preference value to give to this route. Lower values will be preferred over higher values.

Automatic
:    When Automatic is ON, routes from `RA` or `DHCP` are used, but you can also add additional static routes. When OFF, only static routes you define are used.

Use this connection only for resources on its network
:    Select this check box to prevent the connection from becoming the default route. Typical examples are where a connection is a VPN tunnel or a leased line to a head office and you do not want any Internet-bound traffic to pass over the connection. Selecting this option means that only traffic specifically destined for routes learned automatically over the connection or entered here manually will be routed over the connection.

## 2\.3. Using the Command Line Interface (CLI)	{#sec-Using_the_Command_Line_Interface}

### 2\.3.1. Configuring a Network Interface Using ifcfg Files	{#sec-Configuring_a_Network_Interface_Using_ifcg_Files}

Interface configuration files control the software interfaces for individual network devices. As the system boots, it uses these files to determine what interfaces to bring up and how to configure them. These files are usually named ``ifcfg-_`name`_``, where the suffix _`name`_ refers to the name of the device that the configuration file controls. By convention, the `ifcfg` file's suffix, _`ethX`_, is the same as the string given by the **DEVICE** directive in the configuration file itself.

#### Static Network Settings	{#bh-Static_Network_Settings}

To configure an interface with static network settings using `ifcfg` files, for an interface with name eth0, create a file with name `ifcfg-eth0` in the `/etc/sysconfig/network-scripts/` directory as follows:

	DEVICE=eth0
	BOOTPROTO=none
	ONBOOT=yes
	NETMASK=255.255.255.0
	IPADDR=10.0.1.27
	NM_CONTROLLED=no

Optionally specify the hardware or MAC address using the **HWADDR** directive. Note that this will influence the device naming procedure as explained in [Chapter 8, _Consistent Network Device Naming_](#ch-Consistent_Network_Device_Naming "Chapter 8. Consistent Network Device Naming"). You do not need to specify the broadcast address as this is calculated automatically by ipcalc.

#### Dynamic Network Settings	{#bh-Dynamic_Network_Settings}

To configure an interface with dynamic network settings using `ifcfg` files, for an interface with name em1, create a file with name `ifcfg-em1` in the `/etc/sysconfig/network-scripts/` directory as follows:

	DEVICE=em1
	BOOTPROTO=dhcp
	ONBOOT=yes
	NM_CONTROLLED=no

Optionally specify the hardware or MAC address using the **HWADDR** directive. Note that this will influence the device naming procedure as explained in [Chapter 8, _Consistent Network Device Naming_](#ch-Consistent_Network_Device_Naming "Chapter 8. Consistent Network Device Naming"). You do not need to specify the broadcast address as this is calculated automatically by ipcalc.

For a listing of the configurable parameters in an Ethernet interface configuration file see the _Fedora 20 System Administrator's Reference Guide_.

### 2\.3.2. Configuring a Network Interface Using ip Commands	{#sec-Configuring_a_Network_Interface_Using_ip_commands}

The ip utility can be used to assign `IP` addresses to an interface. The command takes the following form:

	ip addr [ add | del ] _`address`_ dev _`ifname`_

#### Assigning a Static Address Using ip Commands	{#bh-Assigning_a_Static_Address_Using_ip_Commands}

To assign an `IP` address to an interface, issue a command as `root` as follows:

	~]# **ip address add 10.0.0.3/24 dev eth0**
	The address assignment of a specific device can be viewed as follows:
	~]# **ip addr show dev eth0**
	2: eth0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UP qlen 1000
	    link/ether f0:de:f1:7b:6e:5f brd ff:ff:ff:ff:ff:ff
	    inet 10.0.0.3/24 brd 10.0.0.255 scope global global eth0
	       valid_lft 58682sec preferred_lft 58682sec
	    inet6 fe80::f2de:f1ff:fe7b:6e5f/64 scope link
	       valid_lft forever preferred_lft forever

Further examples and command options can be found in the `ip-address(8)` manual page.

#### Configuring Multiple Addresses Using ip Commands	{#bh-Configuring_Multiple_Addresses_Using_ip_Commands}

As the ip utility supports assigning multiple addresses to the same interface it is no longer necessary to use the alias interface method of binding multiple addresses to the same interface. The ip command to assign an address can be repeated multiple times in order to assign multiple address. For example:

	~]# **ip address add 192.168.2.223/24 dev eth1**
	~]# **ip address add 192.168.4.223/24 dev eth1**
	~]# **ip addr**
	3: eth1: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UP qlen 1000
	    link/ether 52:54:00:fb:77:9e brd ff:ff:ff:ff:ff:ff
	    inet 192.168.**2**.223/24 scope global eth1
	    inet 192.168.**4**.223/24 scope global eth1

The commands for the ip utility are documented in the `ip(8)` manual page.

### Note

Note that ip commands given on the command line will not persist after a system restart.

### 2\.3.3. Static Routes and the Default Gateway	{#sec-Static-Routes_and_the_Default_Gateway}

Static routes are for traffic that must not, or should not, go through the default gateway. Routing is usually handled by routing devices and therefore it is often not necessary to configure static routes on Fedora servers or clients. Exceptions include traffic that must pass through an encrypted VPN tunnel or traffic that should take a less costly route. The default gateway is for any and all traffic which is not destined for the local network and for which no preferred route is specified in the routing table. The default gateway is traditionally a dedicated network router.

#### Configuring Static Routes Using the Command Line	{#bh-networkscripts-static-routes}

Use the **ip route** command to display the `IP` routing table. If static routes are required, they can be added to the routing table by means of the **ip route add** command and removed using the **ip route del** command. To add a static route to a host address, that is to say to a single `IP` address, issue the following command as `root`:

	ip route add _`192.0.2.1`_

where _`192.0.2.1`_ is the `IP` address of the host in dotted decimal notation. To add a static route to a network, that is to say to an `IP` address representing a range of `IP` addresses, issue the following command as `root`:

	ip route add _`192.0.2.0/24`_

where _`192.0.2.0`_ is the `IP` address of the network in dotted decimal notation and _`/24`_ is the network prefix. The network prefix is the number of enabled bits in the subnet mask. This format of network address slash prefix length is referred to as CIDR notation.

Static route configuration is stored per-interface in a ``/etc/sysconfig/network-scripts/route-_`interface`_`` file. For example, static routes for the eth0 interface would be stored in the `/etc/sysconfig/network-scripts/route-eth0` file. The ``route-_`interface`_`` file has two formats: ip command arguments and network/netmask directives. These are described below.

#### Configuring The Default Gateway	{#bh-networkscripts-default-gateway}

The default gateway is determined by the network scripts which parse the `/etc/sysconfig/network` file first and then the network interface `ifcfg` files for interfaces that are “up”. The `ifcfg` files are parsed in numerically ascending order, and the last GATEWAY directive to be read is used to compose a default route in the routing table.

The default route can thus be indicated by means of the GATEWAY directive and can be specified either globally or in interface-specific configuration files. Specifying the gateway globally has certain advantages in static networking environments, especially if more than one network interface is present. It can make fault finding simpler if applied consistently. There is also the GATEWAYDEV directive, which is a global option. If multiple devices specify GATEWAY, and one interface uses the GATEWAYDEV directive, that directive will take precedence. This option is not recommend as it can have unexpected consequences if an interface goes down and it can complicate fault finding.

In dynamic network environments, where mobile hosts are managed by NetworkManager, gateway information is likely to be interface specific and is best left to be assigned by DHCP. In special cases where it is necessary to influence NetworkManager's selection of the exit interface to be used to reach a gateway, make use of the **DEFROUTE=no** command in the `ifcfg` files for those interfaces which do not lead to the default gateway.

Global default gateway configuration is stored in the `/etc/sysconfig/network` file. This file specifies gateway and host information for all network interfaces. For more information about this file and the directives it accepts, see the _Fedora 20 System Administrator's Reference Guide_.

### 2\.3.4. Configuring Static Routes in ifcfg files	{#sec-Configuring_Static_Routes_in_ifcfg_files}

Static routes set using ip commands on the command line will be lost if the system is shutdown or restarted. To configure static routes to be persistent after a system restart, they must be placed in per-interface configuration files in the `/etc/sysconfig/network-scripts/` directory. The file name should be of the format ``route-_`ethX`_``. There are two types of commands to use in the configuration files; ip commands as explained in [Section 2.3.4, “ Static Routes Using the IP Command Arguments Format ”](#bh-networkscripts-static-routes-ip-command "2.3.4.  Static Routes Using the IP Command Arguments Format") and the _Network/Netmask_ format as explained in [Section 2.3.4, “ Network/Netmask Directives Format”](#bh-networkscripts-static-routes-network-netmask-directives "2.3.4.  Network/Netmask Directives Format").

#### Static Routes Using the IP Command Arguments Format	{#bh-networkscripts-static-routes-ip-command}

If required in a per-interface configuration file, for example `/etc/sysconfig/network-scripts/route-eth0`, define a route to a default gateway on the first line. This is only required if the gateway is not set via `DHCP` and is not set globally in the `/etc/sysconfig/network` file:

	default via _`192.168.1.1`_ `dev` _`interface`_

where _`192.168.1.1`_ is the `IP` address of the default gateway. The _`interface`_ is the interface that is connected to, or can reach, the default gateway. The `dev` option can be omitted, it is optional. Note that this setting takes precedence over a setting in the `/etc/sysconfig/network` file.

If a route to a remote network is required, define a static route. Each line is parsed as an individual route:

	_`10.10.10.0/24`_ via _`192.168.1.1`_ `dev` _`interface`_

where _`10.10.10.0/24`_ is the network address and netmask of the remote network or host. _`192.168.1.1`_ and _`interface`_ are the `IP` address and interface for the gateway leading to the remote network. Add as many static routes as required.

The following is a sample `route-eth0` file using the ip command arguments format. The default gateway is `192.168.0.1`, interface eth0 and a leased line or WAN connection is available at `192.168.0.10`. The two static routes are for reaching the `10.10.10.0/24` network and the `172.16.1.10/32` host:

	default via 192.168.0.1 dev eth0
	10.10.10.0/24 via 192.168.0.10 dev eth0
	172.16.1.10/32 via 192.168.0.10 dev eth0

Static routes should only be configured for remote networks or hosts, that is to say, networks or hosts that are not directly attached to the system. Packets going to the `192.168.0.0/24` network will be directed out the interface attached to that network. Packets to unknown, remote, networks will use the default gateway. Below is an example of setting static routes to a different network, on a machine in the `192.168.0.0/24` network. The example machine has an eth0 interface in the `192.168.0.0/24` network, and an eth1 interface (with address `10.10.10.1`) in the `10.10.10.0/24` network:

	10.10.10.0/24 via 10.10.10.1 dev eth1

Specifying an exit interface is optional. It can be useful if you want to force traffic out of a specific interface. For example, in the case of a VPN, you can force traffic to a remote network to pass through a tun0 interface even when the interface is in a different subnet to the destination network.

### Duplicate default gateways

If the default gateway is already assigned by `DHCP`, the ip command arguments format can cause one of two errors during start-up, or when bringing up an interface from the down state using the **ifup** command: "RTNETLINK answers: File exists" or 'Error: either "to" is a duplicate, or "_`X.X.X.X`_" is a garbage.', where _`X.X.X.X`_ is the gateway, or a different `IP` address. These errors can also occur if you have another route to another network using the default gateway. Both of these errors are safe to ignore.

#### Network/Netmask Directives Format	{#bh-networkscripts-static-routes-network-netmask-directives}

You can also use the network/netmask directives format for ``route-_`interface`_`` files. The following is a template for the network/netmask format, with instructions following afterwards:

	 ADDRESS0=_`10.10.10.0`_ NETMASK0=_`255.255.255.0`_ GATEWAY0=_`192.168.1.1`_

* ``ADDRESS0=_`10.10.10.0`_`` is the network address of the remote network or host to be reached.

* ``NETMASK0=_`255.255.255.0`_`` is the netmask for the network address defined with ``ADDRESS0=_`10.10.10.0`_``.

* ``GATEWAY0=_`192.168.1.1`_`` is the default gateway, or an `IP` address that can be used to reach ``ADDRESS0=_`10.10.10.0`_``

The following is a sample `route-eth0` file using the network/netmask directives format. The default gateway is `192.168.0.1`, interface eth0. The two static routes are for reaching the `10.10.10.0/24` and `172.16.1.0/24` networks. This example is not necessary as traffic trying to reach a remote network or host would use the default gateway anyway:

	ADDRESS0=10.10.10.0
	NETMASK0=255.255.255.0
	GATEWAY0=192.168.0.1
	ADDRESS1=172.16.1.0
	NETMASK1=255.255.255.0
	GATEWAY1=192.168.0.1

Subsequent static routes must be numbered sequentially, and must not skip any values. For example, `ADDRESS0`, `ADDRESS1`, `ADDRESS2`, and so on.

Below is an example of setting static routes to a different network, on a machine in the `192.168.0.0/24` network. The example machine has an eth0 interface in the `192.168.0.0/24` network, and an eth1 interface ( with address `10.10.10.1`) in the `10.10.10.0/24` network:

	ADDRESS0=10.10.10.0
	NETMASK0=255.255.255.0
	GATEWAY0=10.10.10.1

Note that if `DHCP` is used, it can assign these settings automatically.

### 2\.3.5. Configuring IPv6 Tokenized Interface Identifiers	{#sec-Configuring_IPv6_Tokenized_Interface_Identifiers}

In a network, servers are generally given static addresses and these are usually configured manually to avoid relying on a `DHCP` server which may fail or run out of addresses. The `IPv6` protocol introduced _Stateless Address Autoconfiguration_ (SLAAC) which enables clients to assign themselves an address without relying on a `DHCPv6` server. SLAAC derives the `IPv6` address based on the interface hardware, therefore it should not be used for servers in case the hardware is changed and the associated SLAAC generated address changes with it. In an `IPv6` environment, if the network prefix is changed, or the system is moved to a new location, any manually configured static addresses would have to be edited due to the changed prefix.

To address these problems, the IETF draft [_Tokenised IPv6 Identifiers_](https://tools.ietf.org/id/draft-chown-6man-tokenised-ipv6-identifiers-02.txt) has been implemented in the kernel together with corresponding additions to the **ip** utility. This enables the lower 64 bit interface identifier part of the `IPv6` address to be based on a token, supplied by the administrator, leaving the network prefix, the higher 64 bits, to be obtained from _router advertisements_ (RA). This means that if the network interface hardware is changed, the lower 64 bits of the address will not change, and if the system is moved to another network, the network prefix will be obtained from router advertisements automatically, thus no manual editing is required.

To configure an interface to use a tokenized `IPv6` identifier, issue a command in the following format as `root` user:

	~]# **ip token set ::1a:2b:3c:4d/64 dev eth4**

Where `::1a:2b:3c:4d/64` is the token to be used. This setting is not persistent. To make it persistent, add the command to an init script.

Using a memorable token is possible, but is limited to the range of valid hexadecimal digits. For example, for a `DNS` server, which traditionally uses port `53`, a token of `::53/64` could be used.

To view all the configured `IPv6` tokens, issue the following command:

	~]$ **ip token**
	     token :: dev eth0
	     token :: dev eth1
	     token :: dev eth2
	     token :: dev eth3
	     token ::1a:2b:3c:4d dev eth4

To view the configured `IPv6` token for a specific interface, issue the following command:

	~]$ **ip token get dev eth4**
	     token ::1a:2b:3c:4d dev eth4

Note that adding a token to an interface will replace a previously allocated token, and in turn invalidate the address derived from it. Supplying a new token causes a new address to be generated and applied, but this process will leave any other addresses unchanged. In other words, a new tokenized identifier only replaces a previously existing tokenized identifier, not any other `IP` address.

### Note

Take care not to add the same token to more than one system or interface as the duplicate address detection (DAD) mechanism will not be able to resolve the problem. Once a token is set, it cannot be cleared or reset, except by rebooting the machine.

## 2\.4. Using the NetworkManager Command Line Tool, nmcli	{#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli}

The command‐line tool nmcli can be used by both users and scripts for controlling NetworkManager. The basic format of a command is as follows:

	nmcli `OPTIONS` OBJECT { **COMMAND** | help }

where OBJECT can be one of `general`, `networking`, `radio`, `connection`, or `device`. The most used options are: `-t, --terse` for use in scripts, the `-p, --pretty` option for users, and the `-h, --help` option. Command completion has been implemented for nmcli, so remember to press **Tab** when ever you are unsure of the command options available. See the `nmcli(1)` man page for a complete list of the options and commands.

The nmcli tool has some built-in context sensitive help. For example, issue the following two commands and notice the difference:

	~]$ **nmcli help**
	Usage: nmcli [OPTIONS] OBJECT { COMMAND | help }

	OPTIONS
	  -t[erse]                                   terse output
	  -p[retty]                                  pretty output
	  -m[ode] tabular|multiline                  output mode
	  -f[ields] &lt;field1,field2,...&gt;|all|common   specify fields to output
	  -e[scape] yes|no                           escape columns separators in values
	  -n[ocheck]                                 don't check nmcli and NetworkManager versions
	  -a[sk]                                     ask for missing parameters
	  -w[ait] &lt;seconds&gt;                          set timeout waiting for finishing operations
	  -v[ersion]                                 show program version
	  -h[elp]                                    print this help

	OBJECT
	  g[eneral]       NetworkManager's general status and operations
	  n[etworking]    overall networking control
	  r[adio]         NetworkManager radio switches
	  c[onnection]    NetworkManager's connections
	  d[evice]        devices managed by NetworkManager

	~]$ **nmcli general help**
	Usage: nmcli general { COMMAND | help }

	  COMMAND := { status | permissions | logging }

	  status

	  permissions

	  logging [level &lt;log level&gt;] [domains &lt;log domains&gt;]

In the second example above the help is related to the object `general`.

The `nmcli-examples(5)` man page has many useful examples. A brief selection is shown here:

To show the overall status of NetworkManager:

	nmcli general status

To control NetworkManager logging:

	nmcli general logging

To show all connections:

	nmcli connection show

To show only currently active connections, add the `-a, --active` option as follows:

	nmcli connection show --active

To show devices recognized by NetworkManager and their state:

	nmcli device status

Commands can be shortened and some options omitted. For example the command:

	nmcli connection modify id '_`MyCafe`_' 802-11-wireless.mtu 1350

Can be reduced to the following command:

	nmcli con mod _`MyCafe`_ 802-11-wireless.mtu 1350

The `id` option can been omitted because the connection ID (name) is unambiguous for nmcli in this case. As you become familiar with the commands, further abbreviations can be made. For example:

	nmcli connection add type ethernet

can be reduced to:

	nmcli c a type eth

### Note

Remember to use tab completion when in doubt.

### Starting and Stopping an Interface Using nmcli	{#bh-Starting_and_Stopping_an_Interface_Using_nmcli}

The nmcli tool can be used to start and stop any network interface including masters. For example:

	nmcli con up id bond0
	nmcli con up id port0
	nmcli dev disconnect iface bond0
	nmcli dev disconnect iface eth0

### Note

It is recommended to use **nmcli dev disconnect iface _`iface-name`_** rather than **nmcli con down id _`id-string`_** because disconnection places the interface into a “manual” mode, in which no automatic connection will be started until the user tells NetworkManager to start a connection or until an external event like a carrier change, hibernate, or sleep, occurs.

### The nmcli Interactive Connection Editor	{#bh-The_nmcli_Interactive_Connection_Editor}

The nmcli tool has an interactive connection editor. To use it, enter the following command:

	~]$ **nmcli con edit**

You will be prompted to enter a valid connection type from the list displayed. After entering a connection type you will be placed at the nmcli prompt. If you are familiar with the connection types you can add a valid connection `type` option to the **nmcli con edit** command and be taken straight to the nmcli prompt. The format is as follows for editing an existing connection profile:

	nmcli con edit [id | uuid | path] _`ID`_

For adding and editing a new connection profile, the following format applies:

	nmcli con edit [type _`new-connection-type`_] [con-name _`new-connection-name`_]

Type **help** at the nmcli prompt to see a list of valid commands. Use the **describe** command to get a description of settings and their properties. The format is as follows:

	describe _`setting.property`_

For example:

	nmcli&gt; **describe team.config**

### 2\.4.1. Understanding the nmcli Options	{#sec-Understanding_the_nmcli_Options}

Many of the nmcli commands are self-explanatory, however a few command options are worth a moments study:

`type` — The connection type.
:    Allowed values are: `adsl`, `bond`, `bond-slave`, `bridge`, `bridge-slave`, `bluetooth`, `cdma`, `ethernet`, `gsm`, `infiniband`, `olpc-mesh`, `team`, `team-slave`, `vlan`, `wifi`, `wimax`.

Each connection type has type-specific command options. Press **Tab** to see a list of them or see the `TYPE_SPECIFIC_OPTIONS` list in the `nmcli(1)` man page. The `type` option is applicable after the following: **nmcli connection add** and **nmcli connection edit**.

`con-name` — The name assigned to a connection profile.
:    If you do not specify a connection name, one will be generated as follows:

	 `type`-ifname[-number]

The connection name is the name of a _connection profile_ and should not be confused with the interface name that denotes a device (wlan0, eth0, em1, and so on). Users can however name the connections after interfaces, but they are not the same thing. There can be multiple connection profiles available for a device. This is particularly useful for mobile devices or when switching a network cable back and forth between different devices. Rather than edit the configuration, create different profiles and apply them to the interface as needed. The `id` option also refers to the connection profile name.

`id` — An identification string assigned by the user to a connection profile.
:    The ID can be used in **nmcli connection** commands to identify a connection. The NAME field in the output always denotes the connection ID (name). It refers to the same connection profile name that the **con-name** does.

`uuid` — A unique identification string assigned by the system to a connection profile.
:    The UUID can be used in **nmcli connection** commands to identify a connection.

### 2\.4.2. Connecting to a Network Using nmcli	{#sec-Connecting_to_a_Network_Using_nmcli}

To list the currently available network connections, issue a command as follows:

	~]$ **nmcli con show**
	NAME               UUID                     TYPE            TIMESTAMP-REAL
	eth0               4d5c449a-a6c5-451c-8206  802-3-ethernet  Tue 22 Oct 2013 19:50:00 BST
	MyWiFi             91451385-4eb8-4080-8b82  802-11-wireless Tue 22 Oct 2013 08:50:08 BST
	Bond connection 1  720aab83-28dd-4598-9325  bond            never

Note that the NAME field in the output always denotes the connection ID (name). It is not the interface name even though it might look the same. In the example above `eth0` is the connection ID given by the user to the profile applied to the interface eth0. In the second line the user has assigned the connection ID `MyWiFi` to the interface wlan0.

Device status can also be viewed:

	~]$ **nmcli dev status**
	DEVICE      TYPE            STATE
	wlan0      802-11-wireless  connected
	bond0       bond            connecting (getting IP configuration)
	eth0        ethernet        disconnected
	lo          loopback        unmanaged

#### Adding an Ethernet Connection	{#Adding_an_Ethernet_Connection}

To add an Ethernet connection with manual `IP` configuration, issue a command as follows:

	~]$ **nmcli con add con-name _`my-eth1`_ ifname _`eth1`_ type ethernet ip4 192.168.100.100/24 \**
	      **gw4 192.168.100.1**

Optionally, at the same time specify `IPv6` addresses for the device as follows:

	~]$ **nmcli con add con-name _`my-eth1`_ ifname _`eth1`_ type ethernet ip4 192.168.100.100/24 \**
	** gw4 192.168.100.1 ip6 abbe::cafe gw6 2001:db8::1**

To add two `IPv4` `DNS` server addresses:

	~]$ **nmcli con mod _`my-eth1`_ ipv4.dns "8.8.8.8 8.8.4.4"**

To add two `IPv6` `DNS` server addresses:

	~]$ **nmcli con mod _`my-eth1`_ ipv6.dns "2001:4860:4860::8888 2001:4860:4860::8844"**

To bring up the new connection, issue a command as follows:

	~]$ **nmcli -p con up "_`my-eth1`_" ifname _`eth1`_**

To view detailed information about the newly configured connection, issue a command as follows:

	~]$ **nmcli -p con show configured _`my-eth1`_**

To lock a profile to a specific interface, issue a command as follows:

	~]$ **nmcli connection add type ethernet con-name "_`my-eth1`_" ifname eth1**

To make a profile usable for all compatible Ethernet interfaces, issue a command as follows:

	~]$ **nmcli connection add type ethernet con-name "_`my-eth1`_" ifname "*"**

Note that you have to use the `ifname` argument even if you do not want to set a specific interface. Use the wildcard character `*` to specify that the profile can be used with any compatible device.

To lock a profile to a specific MAC address, issue a command as follows:

	~]$ **nmcli connection add type ethernet con-name "_`my-eth1`_" ifname "*" mac 00:00:5E:00:53:00**

#### Adding a Wi-Fi Connection	{#Adding_a_Wi-Fi_Connection}

To view the available Wi-Fi access points, issue a command as follows:

	~]$ **nmcli dev wifi list**
	  SSID            MODE  CHAN  RATE     SIGNAL  BARS  SECURITY
	  FedoraTest     Infra  11    54 MB/s  98      ▂▄▆█  WPA1
	  Red Hat Guest  Infra  6     54 MB/s  97      ▂▄▆█  WPA2
	  Red Hat        Infra  6     54 MB/s  77      ▂▄▆_  WPA2 802.1X
	* Red Hat        Infra  40    54 MB/s  66      ▂▄▆_  WPA2 802.1X
	  VoIP           Infra  1     54 MB/s  32      ▂▄__  WEP
	  MyCafe         Infra  11    54 MB/s  39      ▂▄__  WPA2

To create a Wi-Fi connection profile with manual `IP` configuration, but allowing automatic `DNS` address assignment, issue a command as follows:

	~]$ **nmcli con add con-name _`MyCafe`_ ifname wlan0 type wifi ssid MyCafe \**
	      **p4 192.168.100.101/24 gw4 192.168.100.1**

To set a WPA2 password, for example “caffeine”, issue commands as follows:

	~]$ **nmcli con modify _`MyCafe`_ wifi-sec.key-mgmt wpa-psk**
	~]$ **nmcli con modify _`MyCafe`_ wifi-sec.psk caffeine**

To change Wi-Fi state, issue a command in the following format:

	~]$ **nmcli radio wifi [on | off ]**

#### Changing a Specific Property	{#Changing_a_Specific_Property}

To check a specific property, for example `mtu`, issue a command as follows:

	~]$ **nmcli connection show id '_`MyCafe`_' | grep mtu**
	802-11-wireless.mtu:                     auto

To change the property of a setting, issue a command as follows:

	~]$ **nmcli connection modify id '_`MyCafe`_' 802-11-wireless.mtu 1350**

To verify the change, issue a command as follows:

	~]$ **nmcli connection show id '_`MyCafe`_' | grep mtu**
	802-11-wireless.mtu:                     1350

Note that NetworkManager refers to parameters such as `802-3-ethernet` and `802-11-wireless` as the setting, and `mtu` as a property of the setting. See the `nm-settings(5)` man page for more information on properties and their settings.

## 2\.5. Additional Resources	{#sec-Configure_Networking-additional_resources}

The following sources of information provide additional resources relevant to this chapter.

### 2\.5.1. Installed Documentation	{#sec-Configure_Networking-docs-inst}

* `ip(8)` man page — Describes the ip utility's command syntax.

* `nmcli(1)` man page — Describes NetworkManager's command‐line tool.

* `nmcli-examples(5)` man page — Gives examples of nmcli commands.

* `nm-settings(5)` man page — Describes NetworkManager properties and their settings.

### 2\.5.2. Online Documentation	{#sec-Configure_Networking_Online_Documentation}

[_RFC 1518_](http://www.rfc-editor.org/info/rfc1518) — Classless Inter-Domain Routing (CIDR)
:    Describes the CIDR Address Assignment and Aggregation Strategy, including variable-length subnetting.

[_RFC 1918_](http://www.rfc-editor.org/info/rfc1918) — Address Allocation for Private Internets
:    Describes the range of `IPv4` addresses reserved for private use.

[_RFC 3330_](http://www.rfc-editor.org/info/rfc3330) — Special-Use IPv4 Addresses
:    Describes the global and other specialized `IPv4` address blocks that have been assigned by the Internet Assigned Numbers Authority (IANA).

## Chapter 3. Configure Host Names	{#ch-Configure_Host_Names}

## 3\.1. Understanding Host Names	{#sec_Understanding_Host_Names}

There are three classes of `hostname`: static, pretty, and transient.

The “static” host name is the traditional `hostname`, which can be chosen by the user, and is stored in the `/etc/hostname` file. The “transient” `hostname` is a dynamic host name maintained by the kernel. It is initialized to the static host name by default, whose value defaults to “localhost”. It can be changed by `DHCP` or `mDNS` at runtime. The “pretty” `hostname` is a free-form UTF8 host name for presentation to the user.

### Note

A host name can be a free-form string up to 64 characters in length. However, Red Hat recommends that both static and transient names match the _fully-qualified domain name_ (FQDN) used for the machine in `DNS`, such as `host.example.com`. It is also recommended that the static and transient names consists only of 7 bit ASCII lower-case characters, no spaces or dots, and limits itself to the format allowed for `DNS` domain name labels, even though this is not a strict requirement. Older specifications do not permit the underscore, and so their use is not recommended.

The hostnamectl tool will enforce the following: Static and transient host names to consist of `a-z`, `A-Z`, `0-9`, “`-`”, “`_`” and “`.`” only, to not begin or end in a dot, and to not have two dots immediately following each other. The size limit of 64 characters is enforced.

### 3\.1.1. Recommended Naming Practices	{#sec-Recommended_Naming_Practices}

The Internet Corporation for Assigned Names and Numbers (ICANN) sometimes adds previously unregistered Top-Level Domains (such as `.yourcompany`) to the public register. Therefore, Red Hat strongly recommends that you do not use a domain name that is not delegated to you, even on a private network, as this can result in a domain name that resolves differently depending on network configuration. As a result, network resources can become unavailable. Using domain names that are not delegated to you also makes DNSSEC more difficult to deploy and maintain, as domain name collisions require manual configuration to enable DNSSEC validation. See the [ICANN FAQ on domain name collision](http://www.icann.org/en/help/name-collision/faqs) for more information on this issue.

## 3\.2. Configuring Host Names Using hostnamectl	{#sec_Configuring_Host_Names_Using_hostnamectl}

The hostnamectl tool is provided for administering the three separate classes of host names in use on a given system.

### 3\.2.1. View All the Host Names	{#sec_View_All_the_Host_Names}

To view all the current host names, enter the following command:

	~]$ **hostnamectl status**

The `status` option is implied by default if no option is given.

### 3\.2.2. Set All the Host Names	{#sec_Set_All_the_Host_Names}

To set all the host names on a system, enter the following command as `root`:

	~]# **hostnamectl set-hostname _`name`_**

This will alter the pretty, static, and transient host names alike. The static and transient host names will be simplified forms of the pretty host name. Spaces will be replaced with “`-`” and special characters will be removed.

### 3\.2.3. Set a Particular Host Name	{#sec_Set_a_Particular_Host_Name}

To set a particular host name, enter the following command as `root` with the relevant option:

	~]# **hostnamectl set-hostname _`name`_ [_`option`_...]**

Where _`option`_ is one or more of: `--pretty`, `--static`, and `--transient`.

If the `--static` or `--transient` options are used together with the `--pretty` option, the static and transient host names will be simplified forms of the pretty host name. Spaces will be replaced with “`-`” and special characters will be removed. If the `--pretty` option is not given, no simplification takes place.

When setting a pretty host name, remember to use the appropriate quotation marks if the host name contains spaces or a single quotation mark. For example:

	~]$ **hostnamectl set-hostname "Stephen's notebook" --pretty**

### 3\.2.4. Clear a Particular Host Name	{#sec_Clear_a_Particular_Host_Name}

To clear a particular host name and allow it to revert to the default, enter the following command as `root` with the relevant option:

	~]# **hostnamectl set-hostname _`""`_ [_`option`_...]**

Where _`""`_ is a quoted empty string and where _`option`_ is one or more of: `--pretty`, `--static`, and `--transient`.

### 3\.2.5. Changing Host Names Remotely	{#sec_Changing_Host_Names_Remotely}

To execute a **hostnamectl** command on a remote system, use the `-H, --host` option as follows:

	~]# **hostnamectl set-hostname `-H` [_`username`_]@_`hostname`_**

Where _`hostname`_ is the remote host you wish to configure. The _`username`_ is optional. The hostnamectl tool will use `SSH` to connect to the remote system.

## 3\.3. Additional Resources	{#sec-additional_resources}

The following sources of information provide additional resources regarding hostnamectl.

### 3\.3.1. Installed Documentation	{#sec-hostnamectl-docs-inst}

* `hostnamectl(1)` man page — Describes hostnamectl including the commands and command options.

* `hostname(1)` man page — Contains an explanation of the **hostname** and **domainname** commands.

* `hostname(5)` man page — Contains an explanation of the host name file, its contents, and use.

* `hostname(7)` man page — Contains an explanation of host name resolution.

* `machine-info(5)` man page — Describes the local machine information file and the environment variables it contains.

* `machine-id(5)` man page — Describes the local machine ID configuration file.

* `systemd-hostnamed.service(8)` man page — Describes the `systemd-hostnamed` system service used by hostnamectl.

### 3\.3.2. Online Documentation	{#sec-hostnamectl-Online_Documentation}

<http://www.freedesktop.org/wiki/Software/systemd/hostnamed>
:    Information on `systemd-hostnamed`.

## Chapter 4. Configure Network Bonding	{#ch-Configure_Network_Bonding}

Fedora allows administrators to bind multiple network interfaces together into a single, bonded, channel. Channel bonding enables two or more network interfaces to act as one, simultaneously increasing the bandwidth and providing redundancy.

## 4\.1. Understanding the Default Behavior of Master and Slave Interfaces	{#sec-Bond-Understanding_the_Default_Behavior_of_Master_and_Slave_Interfaces}

When controlling bonded slave interfaces using the `NetworkManager` daemon, and especially when fault finding, keep the following in mind:

1. Starting the master interface does not automatically start the slave interfaces.

1. Starting a slave interface always starts the master interface.

1. Stopping the master interface also stops the slave interfaces.

1. A master without slaves can start static `IP` connections.

1. A master without slaves waits for slaves when starting `DHCP` connections.

1. A master with a `DHCP` connection waiting for slaves completes when a slave with a carrier is added.

1. A master with a `DHCP` connection waiting for slaves continues waiting when a slave without a carrier is added.

## 4\.2. Creating a Bond Connection Using a GUI	{#sec-Creating_a_Bond_Connection_Using_a_GUI}

You can use the GNOME control-center utility to direct NetworkManager to create a Bond from two or more Wired or InfiniBand connections. It is not necessary to create the connections to be bonded first. They can be configured as part of the process to configure the bond. You must have the MAC addresses of the interfaces available in order to complete the configuration process.

### 4\.2.1. Establishing a Bond Connection	{#sec-Establishing_a_Bond_Connection}

Procedure 4.1. Adding a New Bond Connection

You can configure a Bond connection by opening the Network window, clicking the plus symbol, and selecting Bond from the list.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Click the plus symbol to open the selection list. Select Bond. The Editing Bond connection _`1`_ window appears.

1. On the Bond tab, click Add and select the type of interface you want to use with the bond connection. Click the Create button. Note that the dialog to select the slave type only comes up when you create the first slave; after that, it will automatically use that same type for all further slaves.

1. The Editing bond0 slave 1 window appears. Use the Device MAC address drop-down menu to select the MAC address of the interface to be bonded. The first slave's MAC address will be used as the MAC address for the bond interface. If required, enter a clone MAC address to be used as the bond's MAC address. Click the Save button.

1. The name of the bonded slave appears in the Bonded connections window. Click the Add button to add further slave connections.

1. Review and confirm the settings and then click the Save button.

1. Edit the bond-specific settings by referring to [Section 4.2.1.1, “Configuring the Bond Tab”](#sec-Configuring_the_Bond_Tab "4.2.1.1. Configuring the Bond Tab") below.

Procedure 4.2. Editing an Existing Bond Connection

Follow these steps to edit an existing bond connection.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the connection you wish to edit and click the Options button.

1. Select the General tab.

1. Configure the connection name, auto-connect behavior, and availability settings.

    Five settings in the Editing dialog are common to all connection types, see the General tab:

  * Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

  * Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

  * All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

  * Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the drop-down menu.

  * Firewall Zone — Select the firewall zone from the drop-down menu.

1. Edit the bond-specific settings by referring to [Section 4.2.1.1, “Configuring the Bond Tab”](#sec-Configuring_the_Bond_Tab "4.2.1.1. Configuring the Bond Tab") below.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-bond}

Once you have finished editing your bond connection, click the Save button to save your customized configuration. To make NetworkManager apply the changes, power cycle the interface. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking Options to return to the Editing dialog.

Then, to configure:

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"); or,

* `IPv6` settings for the connection, click the IPv6 Settings tab and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

#### 4\.2.1.1. Configuring the Bond Tab	{#sec-Configuring_the_Bond_Tab}

If you have already added a new bond connection (refer to [Procedure 4.1, “Adding a New Bond Connection”](#procedure-Adding_a_New_Bond_Connection "Procedure 4.1. Adding a New Bond Connection") for instructions), you can edit the Bond tab to set the load sharing mode and the type of link monitoring to use to detect failures of a slave connection.

Mode
:    The mode that is used to share traffic over the slave connections which make up the bond. The default is Round-robin. Other load sharing modes, such as `802.3ad`, can be selected by means of the drop-down list.

Link Monitoring
:    The method of monitoring the slaves ability to carry network traffic.

The following modes of load sharing are selectable from the Mode drop-down list:

Round-robin
:    Sets a round-robin policy for fault tolerance and load balancing. Transmissions are received and sent out sequentially on each bonded slave interface beginning with the first one available. This mode might not work behind a bridge with virtual machines without additional switch configuration.

Active backup
:    Sets an active-backup policy for fault tolerance. Transmissions are received and sent out via the first available bonded slave interface. Another bonded slave interface is only used if the active bonded slave interface fails. Note that this is the only mode available for bonds of InfiniBand devices.

XOR
:    Sets an XOR (exclusive-or) policy. Transmissions are based on the selected hash policy. The default is to derive a hash by XOR of the source and destination MAC addresses multiplied by the modulo of the number of slave interfaces. In this mode traffic destined for specific peers will always be sent over the same interface. As the destination is determined by the MAC addresses this method works best for traffic to peers on the same link or local network. If traffic has to pass through a single router then this mode of traffic balancing will be suboptimal.

Broadcast
:    Sets a broadcast policy for fault tolerance. All transmissions are sent on all slave interfaces. This mode might not work behind a bridge with virtual machines without additional switch configuration.

802\.3ad
:    Sets an IEEE `802.3ad` dynamic link aggregation policy. Creates aggregation groups that share the same speed and duplex settings. Transmits and receives on all slaves in the active aggregator. Requires a network switch that is `802.3ad` compliant.

Adaptive transmit load balancing
:    Sets an adaptive Transmit Load Balancing (TLB) policy for fault tolerance and load balancing. The outgoing traffic is distributed according to the current load on each slave interface. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed slave. This mode is only suitable for local addresses known to the kernel bonding module and therefore cannot be used behind a bridge with virtual machines.

Adaptive load balancing
:    Sets an Adaptive Load Balancing (ALB) policy for fault tolerance and load balancing. Includes transmit and receive load balancing for `IPv4` traffic. Receive load balancing is achieved through `ARP` negotiation. This mode is only suitable for local addresses known to the kernel bonding module and therefore cannot be used behind a bridge with virtual machines.

The following types of link monitoring can be selected from the Link Monitoring drop-down list. It is a good idea to test which channel bonding module parameters work best for your bonded interfaces.

MII (Media Independent Interface)
:    The state of the carrier wave of the interface is monitored. This can be done by querying the driver, by querying MII registers directly, or by using ethtool to query the device. Three options are available:

Monitoring Frequency
:    The time interval, in milliseconds, between querying the driver or MII registers.

Link up delay
:    The time in milliseconds to wait before attempting to use a link that has been reported as up. This delay can be used if some gratuitous `ARP` requests are lost in the period immediately following the link being reported as “up”. This can happen during switch initialization for example.

Link down delay
:    The time in milliseconds to wait before changing to another link when a previously active link has been reported as “down”. This delay can be used if an attached switch takes a relatively long time to change to backup mode.

ARP
:    The address resolution protocol (`ARP`) is used to probe one or more peers to determine how well the link-layer connections are working. It is dependent on the device driver providing the transmit start time and the last receive time.

Two options are available:

Monitoring Frequency
:    The time interval, in milliseconds, between sending `ARP` requests.

ARP targets
:    A comma separated list of `IP` addresses to send `ARP` requests to.

## 4\.3. Using the Command Line Interface (CLI)	{#sec-Network_Bonding_Using_the_Command_Line_Interface}

A bond is created using the `bonding` kernel module and a special network interface called a _channel bonding interface_.

### 4\.3.1. Check if Bonding Kernel Module is Installed	{#sec-Check_if_Bonding_Kernel_Module_is_Installed}

In Fedora, the bonding module is not loaded by default. You can load the module by issuing the following command as `root`:

	~]# **modprobe --first-time bonding**

This activation will not persist across system restarts. See the _Fedora 20 System Administrator's Guide_ for an explanation of persistent module loading.

To display information about the module, issue the following command:

	~]$ **modinfo bonding**

See the `modprobe(8)` man page for more command options.

### 4\.3.2. Create a Channel Bonding Interface	{#sec-Create_a_Channel_Bonding_Interface}

To create a channel bonding interface, create a file in the `/etc/sysconfig/network-scripts/` directory called ``ifcfg-bond_`N`_``, replacing _`N`_ with the number for the interface, such as `0`.

The contents of the file can be based on a configuration file for whatever type of interface is getting bonded, such as an Ethernet interface. The essential differences are that the `DEVICE` directive is ``bond_`N`_``, replacing _`N`_ with the number for the interface, and TYPE=Bond. The `NM_CONTROLLED` directive can be added to prevent NetworkManager from configuring this device.

Example 4.1. Example ifcfg-bond0 Interface Configuration File

An example of a channel bonding interface.

	DEVICE=bond0
	NAME=bond0
	TYPE=Bond
	IPADDR=192.168.1.1
	NETMASK=255.255.255.0
	ONBOOT=yes
	BOOTPROTO=none
	BONDING_OPTS="_`bonding parameters separated by spaces`_"

The NAME directive is useful for naming the connection profile in NetworkManager. ONBOOT says whether the profile should be started when booting (or more generally, when auto-connecting a device).

<br />

### Put all Bonding Module Parameters in ifcfg-bondN Files

Parameters for the bonding kernel module must be specified as a space-separated list in the ``BONDING_OPTS="_`bonding parameters`_"`` directive in the ``ifcfg-bond_`N`_`` interface file. Do _not_ specify options for the bonding device in ``/etc/modprobe.d/_`bonding`_.conf``, or in the deprecated `/etc/modprobe.conf` file.

The `max_bonds` parameter is not interface specific and should not be set when using ``ifcfg-bond_`N`_`` files with the **BONDING\_OPTS** directive as this directive will cause the network scripts to create the bond interfaces as required.

For further instructions and advice on configuring the bonding module and to view the list of bonding parameters, see [Section 4.4, “Using Channel Bonding”](#sec-Using_Channel_Bonding "4.4. Using Channel Bonding").

### 4\.3.3. Creating SLAVE Interfaces	{#sec-Creating_SLAVE_Interfaces}

The channel bonding interface is the “master” and the interfaces to be bonded are referred to as the “slaves”. After the channel bonding interface is created, the network interfaces to be bound together must be configured by adding the `MASTER` and `SLAVE` directives to the configuration files of the slaves. The configuration files for each of the slave interfaces can be nearly identical.

Example 4.2. Example Slave Interface Configuration File

For example, if two Ethernet interfaces are being channel bonded, `eth0` and `eth1`, they can both look like the following example:

	DEVICE=eth_`N`_
	NAME=bond0-slave
	TYPE=Ethernet
	BOOTPROTO=none
	ONBOOT=yes
	MASTER=bond0
	SLAVE=yes

In this example, replace _`N`_ with the numerical value for the interface. Note that if more than one profile or configuration file exists with ONBOOT=yes for an interface, they may race with each other and a plain TYPE=Ethernet profile may be activated instead of a bond slave.

<br />

### 4\.3.4. Activating a Channel Bond	{#sec-Activating_a_Channel_Bond}

To activate a bond, bring up all the slaves. As `root`, issue the following commands:

	~]# ** /usr/sbin/ifup ifcfg-eth0**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/7)

	~]# ** /usr/sbin/ifup ifcfg-eth1**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/8)

Note that if editing interface files for interfaces which are currently “up”, set them down first as follows:

	/usr/sbin/ifdown ifcfg-eth_`N`_

Then when complete, bring up all the slaves, which will bring up the bond (provided it was not set “down”).

To make NetworkManager aware of the changes, issue a command for every changed interface as `root`:

	~]# **nmcli con load /etc/sysconfig/network-scripts/ifcfg-_`device`_**

Alternatively, to reload all interfaces:

	~]# **nmcli con reload**

The default behavior is for NetworkManager not to be aware of the changes and to continue using the old configuration data. The is set by the `monitor-connection-files` option in the `NetworkManager.conf` file. See the `NetworkManager.conf(5)` manual page for more information.

To view the status of the bond interface, issue the following command:

	~]# **ip link show**
	1: lo: &lt;LOOPBACK,UP,LOWER_UP&gt; mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
	    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
	2: eth0: &lt;BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:e9:ce:d2 brd ff:ff:ff:ff:ff:ff
	3: eth1: &lt;BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff
	4: bond0: &lt;BROADCAST,MULTICAST,MASTER,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue state UP mode DEFAULT
	    link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff

### 4\.3.5. Creating Multiple Bonds	{#sec-Creating_Multiple_Bonds}

In Fedora 20, for each bond a channel bonding interface is created including the **BONDING\_OPTS** directive. This configuration method is used so that multiple bonding devices can have different configurations. To create multiple channel bonding interfaces, proceed as follows:

* Create multiple ``ifcfg-bond_`N`_`` files with the **BONDING\_OPTS** directive; this directive will cause the network scripts to create the bond interfaces as required.

* Create, or edit existing, interface configuration files to be bonded and include the **SLAVE** directive.

* Assign the interfaces to be bonded, the slave interfaces, to the channel bonding interfaces by means of the **MASTER** directive.

Example 4.3. Example multiple ifcfg-bondN interface configuration files

The following is an example of a channel bonding interface configuration file:

	DEVICE=bondN
	NAME=bondN
	TYPE=Bond
	IPADDR=192.168.1.1
	NETMASK=255.255.255.0
	ONBOOT=yes
	BOOTPROTO=none
	BONDING_OPTS="_`bonding parameters separated by spaces`_"

In this example, replace _`N`_ with the number for the bond interface. For example, to create two bonds create two configuration files, `ifcfg-bond0` and `ifcfg-bond1`, with appropriate `IP` addresses.

<br />

Create the interfaces to be bonded as per [Example 4.2, “Example Slave Interface Configuration File”](#ex-Example_Slave_Interface_Configuration_File "Example 4.2. Example Slave Interface Configuration File") and assign them to the bond interfaces as required using the **MASTER=bond_`N`_** directive. For example, continuing on from the example above, if two interfaces per bond are required, then for two bonds create four interface configuration files and assign the first two using **MASTER=bond_`0`_** and the next two using **MASTER=bond_`1`_**.

## 4\.4. Using Channel Bonding	{#sec-Using_Channel_Bonding}

To enhance performance, adjust available module options to ascertain what combination works best. Pay particular attention to the **miimon** or **arp\_interval** and the **arp\_ip\_target** parameters. See [Section 4.4.1, “Bonding Module Directives”](#s3-modules-bonding-directives "4.4.1. Bonding Module Directives") for a list of available options and how to quickly determine the best ones for your bonded interface.

### 4\.4.1. Bonding Module Directives	{#s3-modules-bonding-directives}

It is a good idea to test which channel bonding module parameters work best for your bonded interfaces before adding them to the _``BONDING_OPTS="_`<bonding parameters>`_"``_ directive in your bonding interface configuration file (`ifcfg-bond0` for example). Parameters to bonded interfaces can be configured without unloading (and reloading) the bonding module by manipulating files in the `sysfs` file system.

`sysfs` is a virtual file system that represents kernel objects as directories, files and symbolic links. `sysfs` can be used to query for information about kernel objects, and can also manipulate those objects through the use of normal file system commands. The `sysfs` virtual file system is mounted under the `/sys/` directory. All bonding interfaces can be configured dynamically by interacting with and manipulating files under the `/sys/class/net/` directory.

In order to determine the best parameters for your bonding interface, create a channel bonding interface file such as `ifcfg-bond0` by following the instructions in [Section 4.3.2, “Create a Channel Bonding Interface”](#sec-Create_a_Channel_Bonding_Interface "4.3.2. Create a Channel Bonding Interface"). Insert the _`SLAVE=yes`_ and _`MASTER=bond0`_ directives in the configuration files for each interface bonded to bond0. Once this is completed, you can proceed to testing the parameters.

First, bring up the bond you created by running **/usr/sbin/ifup ``bond_`<N>`_``** as `root`:

	~]# **/usr/sbin/ifup bond0**

If you have correctly created the `ifcfg-bond0` bonding interface file, you will be able to see `bond0` listed in the output of running ** ip link show** as `root`:

	~]# **ip link show**
	1: lo: &lt;LOOPBACK,UP,LOWER_UP&gt; mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
	    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
	2: eth0: &lt;BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:e9:ce:d2 brd ff:ff:ff:ff:ff:ff
	3: eth1: &lt;BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast master bond0 state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff
	4: bond0: &lt;BROADCAST,MULTICAST,MASTER,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue state UP mode DEFAULT
	    link/ether 52:54:00:38:a6:4c brd ff:ff:ff:ff:ff:ff

To view all existing bonds, even if they are not up, run:

	~]$ **cat /sys/class/net/bonding_masters**
	bond0

You can configure each bond individually by manipulating the files located in the ``/sys/class/net/bond_`<N>`_/bonding/`` directory. First, the bond you are configuring must be taken down:

	~]# **/usr/sbin/ifdown bond0**

As an example, to enable MII monitoring on bond0 with a 1 second interval, run as `root`:

	~]# **echo 1000 &gt; /sys/class/net/bond0/bonding/miimon**

To configure bond0 for _`balance-alb`_ mode, run either:

	~]# **echo 6 &gt; /sys/class/net/bond0/bonding/mode**

...or, using the name of the mode:

	~]# **echo balance-alb &gt; /sys/class/net/bond0/bonding/mode**

After configuring options for the bond in question, you can bring it up and test it by running **/usr/sbin/ifup bond_`<N>`_**. If you decide to change the options, take the interface down, modify its parameters using `sysfs`, bring it back up, and re-test.

Once you have determined the best set of parameters for your bond, add those parameters as a space-separated list to the _`BONDING_OPTS=`_ directive of the ``/etc/sysconfig/network-scripts/ifcfg-bond_`<N>`_ `` file for the bonding interface you are configuring. Whenever that bond is brought up (for example, by the system during the boot sequence if the _`ONBOOT=yes`_ directive is set), the bonding options specified in the _`BONDING_OPTS`_ will take effect for that bond.

The following list provides the names of many of the more common channel bonding parameters, along with a description of what they do. For more information, see the brief descriptions for each `parm` in **modinfo bonding** output, or for more detailed information, see <https://www.kernel.org/doc/Documentation/networking/bonding.txt>.

Bonding Interface Parameters

``ad_select=_`<value>`_ ``
:    Specifies the 802.3ad aggregation selection logic to use. Possible values are:

* **`stable`** or **`0`** — Default setting. The active aggregator is chosen by largest aggregate bandwidth. Reselection of the active aggregator occurs only when all slaves of the active aggregator are down or if the active aggregator has no slaves.

* **`bandwidth`** or **`1`** — The active aggregator is chosen by largest aggregate bandwidth. Reselection occurs if:

  * A slave is added to or removed from the bond;

  * Any slave's link state changes;

  * Any slave's 802.3ad association state changes;

  * The bond's administrative state changes to up.

* **`count`** or **`2`** — The active aggregator is chosen by the largest number of slaves. Reselection occurs as described for the `bandwidth` setting above.

The `bandwidth` and `count` selection policies permit failover of 802.3ad aggregations when partial failure of the active aggregator occurs. This keeps the aggregator with the highest availability, either in bandwidth or in number of slaves, active at all times.

``arp_interval=_`<time_in_milliseconds>`_ ``
:    Specifies, in milliseconds, how often `ARP` monitoring occurs.

### Important

It is essential that both `arp_interval` and `arp_ip_target` parameters are specified, or, alternatively, the `miimon` parameter is specified. Failure to do so can cause degradation of network performance in the event that a link fails.

If using this setting while in `mode=0` or `mode=1` (the two load-balancing modes), the network switch must be configured to distribute packets evenly across the NICs. For more information on how to accomplish this, see <https://www.kernel.org/doc/Documentation/networking/bonding.txt>.

The value is set to **`0`** by default, which disables it.

``arp_ip_target=_`<ip_address>`_[,_`<ip_address_2>`_,…_`<ip_address_16>`_] ``
:    Specifies the target `IP` address of `ARP` requests when the `arp_interval` parameter is enabled. Up to 16 `IP` addresses can be specified in a comma separated list.

``arp_validate=_`<value>`_ ``
:    Validate source/distribution of `ARP` probes; default is **`none`**. Other valid values are **`active`**, **`backup`**, and **`all`**.

``downdelay=_`<time_in_milliseconds>`_ ``
:    Specifies (in milliseconds) how long to wait after link failure before disabling the link. The value must be a multiple of the value specified in the `miimon` parameter. The value is set to **`0`** by default, which disables it.

``fail_over_mac=_`<value>`_ ``
:    Specifies whether active-backup mode should set all slaves to the same MAC address at enslavement (the traditional behavior), or, when enabled, perform special handling of the bond's MAC address in accordance with the selected policy. Possible values are:

* **`none`** or **`0`** — Default setting. This setting disables `fail_over_mac`, and causes bonding to set all slaves of an active-backup bond to the same MAC address at enslavement time.

* **`active`** or **`1`** — The “active”&gt; `fail_over_mac` policy indicates that the MAC address of the bond should always be the MAC address of the currently active slave. The MAC address of the slaves is not changed; instead, the MAC address of the bond changes during a failover.

    This policy is useful for devices that cannot ever alter their MAC address, or for devices that refuse incoming broadcasts with their own source MAC (which interferes with the ARP monitor). The disadvantage of this policy is that every device on the network must be updated via gratuitous ARP, as opposed to the normal method of switches snooping incoming traffic to update their ARP tables. If the gratuitous ARP is lost, communication may be disrupted.

    When this policy is used in conjunction with the MII monitor, devices which assert link up prior to being able to actually transmit and receive are particularly susceptible to loss of the gratuitous ARP, and an appropriate updelay setting may be required.

* **`follow`** or **`2`** — The “follow” `fail_over_mac` policy causes the MAC address of the bond to be selected normally (normally the MAC address of the first slave added to the bond). However, the second and subsequent slaves are not set to this MAC address while they are in a backup role; a slave is programmed with the bond's MAC address at failover time (and the formerly active slave receives the newly active slave's MAC address).

    This policy is useful for multiport devices that either become confused or incur a performance penalty when multiple ports are programmed with the same MAC address.

lacp\_rate=_`<value>`_
:    Specifies the rate at which link partners should transmit LACPDU packets in 802.3ad mode. Possible values are:

* **`slow`** or **`0`** — Default setting. This specifies that partners should transmit LACPDUs every 30 seconds.

* **`fast`** or **`1`** — Specifies that partners should transmit LACPDUs every 1 second.

``miimon=_`<time_in_milliseconds>`_ ``
:    Specifies (in milliseconds) how often MII link monitoring occurs. This is useful if high availability is required because MII is used to verify that the NIC is active. To verify that the driver for a particular NIC supports the MII tool, type the following command as root:

	~]# **ethtool _`<interface_name>`_ | grep "Link detected:"**

In this command, replace _`<interface_name`_&gt; with the name of the device interface, such as **`eth0`**, not the bond interface. If MII is supported, the command returns:

	Link detected: yes

If using a bonded interface for high availability, the module for each NIC must support MII. Setting the value to **`0`** (the default), turns this feature off. When configuring this setting, a good starting point for this parameter is **`100`**.

### Important

It is essential that both `arp_interval` and `arp_ip_target` parameters are specified, or, alternatively, the `miimon` parameter is specified. Failure to do so can cause degradation of network performance in the event that a link fails.

``mode=_`<value>`_ ``
:    Allows you to specify the bonding policy. The _`<value>`_ can be one of:

* **`balance-rr`** or **`0`** — Sets a round-robin policy for fault tolerance and load balancing. Transmissions are received and sent out sequentially on each bonded slave interface beginning with the first one available.

* **`active-backup`** or **`1`** — Sets an active-backup policy for fault tolerance. Transmissions are received and sent out via the first available bonded slave interface. Another bonded slave interface is only used if the active bonded slave interface fails.

* **`balance-xor`** or **`2`** — Transmissions are based on the selected hash policy. The default is to derive a hash by XOR of the source and destination MAC addresses multiplied by the modulo of the number of slave interfaces. In this mode traffic destined for specific peers will always be sent over the same interface. As the destination is determined by the MAC addresses this method works best for traffic to peers on the same link or local network. If traffic has to pass through a single router then this mode of traffic balancing will be suboptimal.

* **`broadcast`** or **`3`** — Sets a broadcast policy for fault tolerance. All transmissions are sent on all slave interfaces.

* **`802.3ad`** or **`4`** — Sets an IEEE 802.3ad dynamic link aggregation policy. Creates aggregation groups that share the same speed and duplex settings. Transmits and receives on all slaves in the active aggregator. Requires a switch that is 802.3ad compliant.

* **`balance-tlb`** or **`5`** — Sets a Transmit Load Balancing (TLB) policy for fault tolerance and load balancing. The outgoing traffic is distributed according to the current load on each slave interface. Incoming traffic is received by the current slave. If the receiving slave fails, another slave takes over the MAC address of the failed slave. This mode is only suitable for local addresses known to the kernel bonding module and therefore cannot be used behind a bridge with virtual machines.

* **`balance-alb`** or **`6`** — Sets an Adaptive Load Balancing (ALB) policy for fault tolerance and load balancing. Includes transmit and receive load balancing for `IPv4` traffic. Receive load balancing is achieved through `ARP` negotiation. This mode is only suitable for local addresses known to the kernel bonding module and therefore cannot be used behind a bridge with virtual machines.

``primary=_`<interface_name>`_ ``
:    Specifies the interface name, such as **`eth0`**, of the primary device. The `primary` device is the first of the bonding interfaces to be used and is not abandoned unless it fails. This setting is particularly useful when one NIC in the bonding interface is faster and, therefore, able to handle a bigger load.

This setting is only valid when the bonding interface is in **`active-backup`** mode. See <https://www.kernel.org/doc/Documentation/networking/bonding.txt> for more information.

``primary_reselect=_`<value>`_ ``
:    Specifies the reselection policy for the primary slave. This affects how the primary slave is chosen to become the active slave when failure of the active slave or recovery of the primary slave occurs. This parameter is designed to prevent flip-flopping between the primary slave and other slaves. Possible values are:

* **`always`** or **`0`** (default) — The primary slave becomes the active slave whenever it comes back up.

* **`better`** or **`1`** — The primary slave becomes the active slave when it comes back up, if the speed and duplex of the primary slave is better than the speed and duplex of the current active slave.

* **`failure`** or **`2`** — The primary slave becomes the active slave only if the current active slave fails and the primary slave is up.

The `primary_reselect` setting is ignored in two cases:

* If no slaves are active, the first slave to recover is made the active slave.

* When initially enslaved, the primary slave is always made the active slave.

Changing the `primary_reselect` policy via `sysfs` will cause an immediate selection of the best active slave according to the new policy. This may or may not result in a change of the active slave, depending upon the circumstances

``resend_igmp=_`range`_``
:    Specifies the number of IGMP membership reports to be issued after a failover event. One membership report is issued immediately after the failover, subsequent packets are sent in each 200ms interval.

The valid range is `0` to `255`; the default value is `1`. A value of `0` prevents the IGMP membership report from being issued in response to the failover event.

This option is useful for bonding modes **balance-rr** (mode 0), **active-backup** (mode 1), **balance-tlb** (mode 5) and **balance-alb** (mode 6), in which a failover can switch the IGMP traffic from one slave to another. Therefore a fresh IGMP report must be issued to cause the switch to forward the incoming IGMP traffic over the newly selected slave.

``updelay=_`<time_in_milliseconds>`_ ``
:    Specifies (in milliseconds) how long to wait before enabling a link. The value must be a multiple of the value specified in the `miimon` parameter. The value is set to **`0`** by default, which disables it.

``use_carrier=_`<number>`_ ``
:    Specifies whether or not `miimon` should use MII/ETHTOOL ioctls or `netif_carrier_ok()` to determine the link state. The `netif_carrier_ok()` function relies on the device driver to maintains its state with ``netif_carrier__`on/off`_``; most device drivers support this function.

The MII/ETHTOOL ioctls tools utilize a deprecated calling sequence within the kernel. However, this is still configurable in case your device driver does not support ``netif_carrier__`on/off`_``.

Valid values are:

* **`1`** — Default setting. Enables the use of `netif_carrier_ok()`.

* **`0`** — Enables the use of MII/ETHTOOL ioctls.

### Note

If the bonding interface insists that the link is up when it should not be, it is possible that your network device driver does not support ``netif_carrier__`on/off`_``.

``xmit_hash_policy=_`<value>`_ ``
:    Selects the transmit hash policy used for slave selection in **`balance-xor`** and **`802.3ad`** modes. Possible values are:

* **`0`** or **`layer2`** — Default setting. This parameter uses the XOR of hardware MAC addresses to generate the hash. The formula used is:

	(_`<source_MAC_address>`_ XOR _`<destination_MAC>`_) MODULO _`<slave_count>`_

    This algorithm will place all traffic to a particular network peer on the same slave, and is 802.3ad compliant.

* **`1`** or **`layer3+4`** — Uses upper layer protocol information (when available) to generate the hash. This allows for traffic to a particular network peer to span multiple slaves, although a single connection will not span multiple slaves.

    The formula for unfragmented TCP and UDP packets used is:

	((_`<source_port>`_ XOR _`<dest_port>`_) XOR
	  ((_`<source_IP>`_ XOR _`<dest_IP>`_) AND `0xffff`)
	    MODULO _`<slave_count>`_

    For fragmented TCP or UDP packets and all other `IP` protocol traffic, the source and destination port information is omitted. For non-`IP` traffic, the formula is the same as the **layer2** transmit hash policy.

    This policy intends to mimic the behavior of certain switches; particularly, Cisco switches with PFC2 as well as some Foundry and IBM products.

    The algorithm used by this policy is not 802.3ad compliant.

* **`2`** or **`layer2+3`** — Uses a combination of layer2 and layer3 protocol information to generate the hash.

    Uses XOR of hardware MAC addresses and `IP` addresses to generate the hash. The formula is:

	(((_`<source_IP>`_ XOR _`<dest_IP>`_) AND `0xffff`) XOR
	  ( _`<source_MAC>`_ XOR _`<destination_MAC>`_ ))
	    MODULO _`<slave_count>`_

    This algorithm will place all traffic to a particular network peer on the same slave. For non-`IP` traffic, the formula is the same as for the layer2 transmit hash policy.

    This policy is intended to provide a more balanced distribution of traffic than layer2 alone, especially in environments where a layer3 gateway device is required to reach most destinations.

    This algorithm is 802.3ad compliant.

## 4\.5. Using the NetworkManager Command Line Tool, nmcli	{#sec-Network_Bonding_Using_the_NetworkManager_Command_Line_Tool_nmcli}

To create a bond, named _`mybond0`_, issue a command as follows:

	~]$ **nmcli con add type bond con-name _`mybond0`_ ifname _`mybond0`_ mode active-backup**
	Connection 'mybond0' (9301ff97-abbc-4432-aad1-246d7faea7fb) successfully added.

To add a slave interface, issue a command in the following form:

	~]$ **nmcli con add type bond-slave ifname _`ens7`_ master _`mybond0`_**

To add additional slaves, repeat the previous command with a new interface, for example:

	~]$ **nmcli con add type bond-slave ifname _`ens3`_ master _`mybond0`_**
	Connection 'bond-slave-ens3-1' (50c59350-1531-45f4-ba04-33431c16e386) successfully added.

Note that as no **con-name** was given for the slaves, the name was derived from the interface name by prepending the type. At time of writing, nmcli only supports Ethernet slaves.

In order to bring up a bond, the slaves must be brought up first as follows:

	~]$ **nmcli con up bond-slave-_`ens7`_**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/14)

	~]$ **nmcli con up bond-slave-_`ens3`_**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/15)

Now bring up the bond as follows:

	~]$ **nmcli con up bond-_`mybond0`_**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/16)

See [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli") for an introduction to nmcli

## 4\.6. Additional Resources	{#sec-Configure_Network_Bonding-additional_resources}

The following sources of information provide additional resources regarding network bonding.

### 4\.6.1. Installed Documentation	{#sec-Configure_Network_Bonding-docs-inst}

* `nmcli(1)` man page — Describes NetworkManager's command‐line tool.

* `nmcli-examples(5)` man page — Gives examples of nmcli commands.

* `nm-settings(5)` man page — Description of settings and parameters of NetworkManager connections.

### 4\.6.2. Installable Documentation	{#sec-Configure_Network_Bonding-docs-installable}

* `/usr/share/doc/kernel-doc/Documentation/` — This directory, which is provided by the kernel-doc package, contains information on bonding. Before accessing the kernel documentation, you must run the following command as `root`:

	~]# **yum install kernel-doc**

    ``/usr/share/doc/kernel-doc-_`version`_/Documentation/networking/bonding.txt`` — Describes the Linux bonding driver.

### 4\.6.3. Online Documentation	{#sec-Configure_Network_Bonding_Online_Documentation}

_Fedora 20 System Administrator's Reference Guide_
:    Lists all the configurable parameters in an Ethernet interface configuration file.

_Fedora 20 System Administrator's Guide_
:    Explains the use of kernel module capabilities.

## Chapter 5. Configure Network Teaming	{#ch-Configure_Network_Teaming}

## 5\.1. Understanding Network Teaming	{#sec-Understanding_Network_Teaming}

The combining or aggregating together of network links in order to provide a logical link with higher throughput, or to provide redundancy, is known by many names such as “channel bonding”, “Ethernet bonding”, “port trunking”, “channel teaming”, “NIC teaming”, “link aggregation”, and so on. This concept as originally implemented in the Linux kernel is widely referred to as “bonding”. The term Network Teaming has been chosen to refer to this new implementation of the concept. The existing bonding driver is unaffected, Network Teaming is offered as an alternative and does not replace bonding in Fedora.

Network Teaming, or Team, is designed to implement the concept in a different way by providing a small kernel driver to implement the fast handling of packet flows, and various user-space applications to do everything else in user space. The driver has an _Application Programming Interface_ (API), referred to as “Team Netlink API”, which implements Netlink communications. User-space applications can use this API to communicate with the driver. A library, referred to as “lib”, has been provided to do user space wrapping of Team Netlink communications and RT Netlink messages. An application daemon, `teamd`, which uses Libteam lib is also provided. One instance of `teamd` can control one instance of the Team driver. The daemon implements the load-balancing and active-backup logic, such as round-robin, by using additional code referred to as “runners”. By separating the code in this way, the Network Teaming implementation presents an easily extensible and scalable solution for load-balancing and redundancy requirements. For example, custom runners can be relatively easily written to implement new logic via `teamd`, and even `teamd` is optional, users can write their own application to use libteam.

A tool to control a running instance of `teamd` using D-bus is provided by teamdctl. It provides a D-Bus wrapper around the `teamd` D-Bus API. By default, `teamd` listens and communicates using Unix Domain Sockets but still monitors D-Bus. This is to insure that `teamd` can be used in environments where D-Bus is not present or not yet loaded. For example, when booting over `teamd` links D-Bus would not yet be loaded. The teamdctl tool can be used during run time to read the configuration, the state of link-watchers, check and change the state of ports, add and remove ports, and to change ports between active and backup states.

Team Netlink API communicates with user-space applications using Netlink messages. The user-space library libteam does not directly interact with the API, but uses libnl or teamnl to interact with the driver API.

To sum up, the instances of Team driver, running in the kernel, do not get configured or controlled directly. All configuration is done with the aid of user space applications, such as the teamd application. The application then directs the kernel driver part accordingly.

## 5\.2. Comparison of Network Teaming to Bonding	{#sec-Comparison_of_Network_Teaming_to_Bonding}

Table 5.1. A Comparison of Features in Bonding and Team

|Feature|Bonding|Team|
|-|
|broadcast Tx policy|Yes|Yes|
|round-robin Tx policy|Yes|Yes|
|active-backup Tx policy|Yes|Yes|
|LACP (802.3ad) support|Yes (passive only)|Yes|
|Hash-based Tx policy|Yes|Yes|
|User can set hash function|No|Yes|
|Tx load-balancing support (TLB)|Yes|Yes|
|LACP hash port select|Yes|Yes|
|load-balancing for LACP support|No|Yes|
|Ethtool link monitoring|Yes|Yes|
|ARP link monitoring|Yes|Yes|
|NS/NA (IPv6) link monitoring|No|Yes|
|ports up/down delays|Yes|Yes|
|port priorities and stickiness (“primary” option enhancement)|No|Yes|
|separate per-port link monitoring setup|No|Yes|
|multiple link monitoring setup|Limited|Yes|
|lockless Tx/Rx path|No (rwlock)|Yes (RCU)|
|VLAN support|Yes|Yes|
|user-space runtime control|Limited|Full|
|Logic in user-space|No|Yes|
|Extensibility|Hard|Easy|
|Modular design|No|Yes|
|Performance overhead|Low|Very Low|
|D-Bus interface|No|Yes|
|multiple device stacking|Yes|Yes|
|zero config using LLDP|No|(in planning)|
|NetworkManager support|Yes|Yes|

<br />

## 5\.3. Understanding the Default Behavior of Master and Slave Interfaces	{#sec-Team-Understanding_the_Default_Behavior_of_Master_and_Slave_Interfaces}

When controlling teamed port interfaces using the `NetworkManager` daemon, and especially when fault finding, keep the following in mind:

1. Starting the master interface does not automatically start the port interfaces.

1. Starting a port interface always starts the master interface.

1. Stopping the master interface also stops the port interfaces.

1. A master without ports can start static `IP` connections.

1. A master without ports waits for ports when starting `DHCP` connections.

1. A master with a `DHCP` connection waiting for ports completes when a port with a carrier is added.

1. A master with a `DHCP` connection waiting for ports continues waiting when a port without a carrier is added.

## 5\.4. Understanding the Network Teaming Daemon and the "Runners"	{#sec-Understanding_the_Network_Teaming_Daemon_and_the_Runners}

The Team daemon, `teamd`, uses libteam to control one instance of the team driver. This instance of the team driver adds instances of a hardware device driver to form a “team” of network links. The team driver presents a network interface, team0 for example, to the other parts of the kernel. The interfaces created by instances of the team driver are given names such as team0, team1, and so forth in the documentation. This is for ease of understanding and other names can be used. The logic common to all methods of teaming is implemented by `teamd`; those functions that are unique to the different load sharing and backup methods, such as round-robin, are implemented by separate units of code referred to as “runners”. Because words such as “module” and “mode” already have specific meanings in relation to the kernel, the word “runner” was chosen to refer to these units of code. The user specifies the runner in the JSON format configuration file and the code is then compiled into an instance of `teamd` when the instance is created. A runner is not a plug-in because the code for a runner is compiled into an instance of `teamd` as it is being created. Code could be created as a plug-in for `teamd` should the need arise.

The following runners are available at time of writing.

* broadcast (data is transmitted over all ports)

* round-robin (data is transmitted over all ports in turn)

* active-backup (one port or link is used while others are kept as a backup)

* loadbalance (with active Tx load balancing and BPF-based Tx port selectors)

* lacp (implements the 802.3ad Link Aggregation Control Protocol)

In addition, the following link-watchers are available:

* ethtool (Libteam lib uses ethtool to watch for link state changes). This is the default if no other link-watcher is specified in the configuration file.

* arp\_ping (The arp\_ping utility is used to monitor the presence of a far-end hardware address using ARP packets.)

* nsna\_ping (Neighbor Advertisements and Neighbor Solicitation from the `IPv6` Neighbor Discovery protocol are used to monitor the presence of a neighbor's interface)

There are no restrictions in the code to prevent a particular link-watcher from being used with a particular runner, however when using the lacp runner, ethtool is the only recommended link-watcher.

## 5\.5. Install the Network Teaming Daemon	{#sec-Install_the_Network_Teaming_Daemon}

The networking teaming daemon, `teamd`, is not installed by default. To install `teamd`, issue the following command as `root`:

	~]# **yum install teamd**

## 5\.6. Converting a Bond to a Team	{#sec-Converting_a_Bond_to_a_Team}

It is possible to convert existing bonding configuration files to team configuration files using the bond2team tool. It can convert bond configuration files in `ifcfg` format to team configuration files in either `ifcfg` or JSON format. Note that firewall rules, alias interfaces, and anything that might be tied to the original interface name can break after the renaming because the tool will only change the `ifcfg` file, nothing else.

To see some examples of the command format, issue the following command:

	~]$ **bond2team --examples**

New files will be created in a directory whose name starts with `/tmp/bond2team.XXXXXX/`, where XXXXXX is a random string. After creating the new configuration files, move the old bonding files to a backup folder and then move the new files to the `/etc/sysconfig/network-scripts/` directory. See the `bond2team(1)` man page for further details.

## 5\.7. Selecting Interfaces to Use as Ports for a Network Team	{#sec-Selecting_Interfaces_to_Use_as_Port_for_a_Network_Team}

To view the available interfaces, issue the following command:

	~]$ **ip link show**
	1: lo:  &lt;LOOPBACK,UP,LOWER_UP &gt; mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
	    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
	2: em1:  &lt;BROADCAST,MULTICAST,UP,LOWER_UP &gt; mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:6a:02:8a brd ff:ff:ff:ff:ff:ff
	3: em2:  &lt;BROADCAST,MULTICAST,UP,LOWER_UP &gt; mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
	link/ether 52:54:00:9b:6d:2a brd ff:ff:ff:ff:ff:ff

From the available interfaces, determine which are suitable for adding to your network team and then proceed to [Section 5.8, “Selecting Network Team Configuration Methods”](#sec-Selecting_Network_Team_Configuration_Methods "5.8. Selecting Network Team Configuration Methods")

### Note

The Team developers prefer the term “port” rather than “slave”, however NetworkManager uses the term “team-slave” to refer to interfaces that make up a team.

## 5\.8. Selecting Network Team Configuration Methods	{#sec-Selecting_Network_Team_Configuration_Methods}

**To configure a network team using a graphical user interface**, see [Section 5.9, “Creating a Network Team Using a GUI”](#sec-Creating_a_Network_Team_Using_a_GUI "5.9. Creating a Network Team Using a GUI")

**To create a network team using the Team daemon**, `teamd`, proceed to [Section 5.10.1, “Creating a Network Team Using teamd”](#sec-Creating_a_Network_Team_Using_teamd "5.10.1. Creating a Network Team Using teamd").

**To create a network team using configuration files**, proceed to [Section 5.10.2, “Creating a Network Team Using ifcfg Files”](#sec-Creating_a_Network_Team_Using_ifcfg_Files "5.10.2. Creating a Network Team Using ifcfg Files").

**To create a network team using the command-line tool**, nmcli, proceed to [Section 5.13, “Configure Network Teaming Using nmcli”](#sec-Configure_Network_Teaming_Using_nmcli "5.13. Configure Network Teaming Using nmcli").

## 5\.9. Creating a Network Team Using a GUI	{#sec-Creating_a_Network_Team_Using_a_GUI}

### 5\.9.1. Establishing a Team Connection	{#sec-Establishing_a_Team_Connection}

You can use the GNOME control-center utility to direct NetworkManager to create a team from two or more Wired or InfiniBand connections. It is not necessary to create the connections to be teamed first. They can be configured as part of the process to configure the team. You must have the MAC addresses of the interfaces available in order to complete the configuration process.

Procedure 5.1. Adding a New Team Connection

You can configure a team connection by opening the Network window, clicking the plus symbol, and selecting Team from the list.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Click the plus symbol to open the selection list. Select Team. The Editing Team Connection _`1`_ window appears.

1. On the Team tab, click Add and select the type of interface you want to use with the team connection. Click the Create button. Note that the dialog to select the port type only comes up when you create the first port; after that, it will automatically use that same type for all further ports.

1. The Editing team0 port 1 window appears. Fill in the MAC address of the first interface to be added to the team.

1. If custom port settings are to be applied, click on the Team Port tab and enter a JSON configuration string or import it from a file.

1. Click the Save button.

1. The name of the teamed port appears in the Teamed connections window. Click the Add button to add further port connections.

1. Review and confirm the settings and then click the Save button.

1. Edit the team-specific settings by referring to [Section 5.9.1.1, “Configuring the Team Tab”](#sec-Configuring_the_Team_Tab "5.9.1.1. Configuring the Team Tab") below.

Procedure 5.2. Editing an Existing Team Connection

Follow these steps to edit an existing bond connection.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the connection you wish to edit and click the Options button.

1. Select the General tab.

1. Configure the connection name, auto-connect behavior, and availability settings.

    Five settings in the Editing dialog are common to all connection types, see the General tab:

  * Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

  * Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

  * All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

  * Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the drop-down menu.

  * Firewall Zone — Select the firewall zone from the drop-down menu.

1. Edit the team-specific settings by referring to [Section 5.9.1.1, “Configuring the Team Tab”](#sec-Configuring_the_Team_Tab "5.9.1.1. Configuring the Team Tab") below.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-team}

Once you have finished editing your team connection, click the Save button to save your customized configuration. To make NetworkManager apply the changes, power cycle the interface. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking Options to return to the Editing dialog.

Then, to configure:

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"); or,

* IPv6 settings for the connection, click the IPv6 Settings tab and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

#### 5\.9.1.1. Configuring the Team Tab	{#sec-Configuring_the_Team_Tab}

If you have already added a new team connection you can enter a custom JSON configuration string in the text box or import a configuration file. Click Save to apply the JSON configuration to the team interface.

For examples of JSON strings, see [Section 5.12, “Configure teamd Runners”](#sec-Configure_teamd_Runners "5.12. Configure teamd Runners")

See [Procedure 5.1, “Adding a New Team Connection”](#procedure-Adding_a_New_Team_Connection "Procedure 5.1. Adding a New Team Connection") for instructions on how to add a new team.

## 5\.10. Configure a Network Team Using the Command Line	{#sec-Configure_a_Network_Team_Using-the_Command_Line}

### 5\.10.1. Creating a Network Team Using teamd	{#sec-Creating_a_Network_Team_Using_teamd}

To create a network team, a JSON format configuration file is required for the virtual interface that will serve as the interface to the team of ports or links. A quick way is to copy the example configuration files and then edit them using an editor running with `root` privileges. To list the available example configurations, enter the following command:

	~]$ **ls /usr/share/doc/teamd-*/example_configs/**
	activebackup_arp_ping_1.conf  activebackup_multi_lw_1.conf   loadbalance_2.conf
	activebackup_arp_ping_2.conf  activebackup_nsna_ping_1.conf  loadbalance_3.conf
	activebackup_ethtool_1.conf   broadcast.conf                 random.conf
	activebackup_ethtool_2.conf   lacp_1.conf                    roundrobin_2.conf
	activebackup_ethtool_3.conf   loadbalance_1.conf             roundrobin.conf

To view one of the included files, such as `activebackup_ethtool_1.conf`, enter the following command:

	~]$ **cat /usr/share/doc/teamd-*/example_configs/activebackup_ethtool_1.conf**
	{
		"device":	"team0",
		"runner":	{"name": "activebackup"},
		"link_watch":	{"name": "ethtool"},
		"ports":	{
			"eth1": {
				"prio": -10,
				"sticky": true
			},
			"eth2": {
				"prio": 100
			}
		}
	}

Create a working configurations directory to store `teamd` configuration files. For example, as normal user, enter a command with the following format:

	~]$ **mkdir ~/_`teamd_working_configs`_**

Copy the file you have chosen to your working directory and edit it as necessary. As an example, you could use a command with the following format:

	~]$ **cp /usr/share/doc/teamd-*/example_configs/activebackup_ethtool_1.conf \ ~/_`teamd_working_configs`_/activebackup_ethtool_1.conf**

To edit the file to suit your environment, for example to change the interfaces to be used as ports for the network team, open the file for editing as follows:

	~]$ **vi ~/_`teamd_working_configs`_/activebackup_ethtool_1.conf**

Make any necessary changes and save the file. See the `vi(1)` man page for help on using the vi editor or use your preferred editor.

Note that it is essential that the interfaces to be used as ports within the team must not be active, that is to say, they must be “down”, when adding them into a team device. To check their status, issue the following command:

	~]$ **ip link show**
	1: lo: &lt;LOOPBACK,UP,LOWER_UP&gt; mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT
	    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
	2: em1: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
	    link/ether 52:54:00:d5:f7:d4 brd ff:ff:ff:ff:ff:ff
	3: em2: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000
	  link/ether 52:54:00:d8:04:70 brd ff:ff:ff:ff:ff:ff

In this example we see that both the interfaces we plan to use are “UP”.

To take down an interface, issue a command as `root` in the following format:

	~]# **ip link set down em1**

Repeat for each interface as necessary.

To create a team interface based on the configuration file, as `root` user, change to the working configurations directory (_`teamd_working_configs`_ in this example):

	~]# **cd /home/_`user`__`teamd_working_configs`_**

Then issue a command in the following format:

	~]# **teamd -g -f activebackup_ethtool_1.conf -d**
	Using team device "team0".
	Using PID file "/var/run/teamd/team0.pid"
	Using config file "/home/_`user`_/teamd_working_configs/activebackup_ethtool_1.conf"

The `-g` option is for debug messages, `-f` option is to specify the configuration file to load, and the `-d` option is to make the process run as a daemon after startup. See the `teamd(8)` man page for other options.

To check the status of the team, issue the following command as `root`:

	~]# **teamdctl team0 state**
	setup:
	  runner: activebackup
	ports:
	  em1
	    link watches:
	      link summary: up
	      instance[link_watch_0]:
	        name: ethtool
	        link: up
	  em2
	    link watches:
	      link summary: up
	      instance[link_watch_0]:
	        name: ethtool
	        link: up
	runner:
	  active port: em1

To apply an address to the network team interface, team0, issue a command as `root` in the following format:

	~]# **ip addr add 192.168.23.2/24 dev team0**

To check the IP address of a team interface, issue a command as follows:

	~]$ **ip addr show team0**
	4: team0:  &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue state UP
	    link/ether 16:38:57:60:20:6f brd ff:ff:ff:ff:ff:ff
	    inet 192.168.23.2/24 scope global team0
	       valid_lft forever preferred_lft forever
	    inet6 2620:52:0:221d:1438:57ff:fe60:206f/64 scope global dynamic
	       valid_lft 2591880sec preferred_lft 604680sec
	    inet6 fe80::1438:57ff:fe60:206f/64 scope link
	       valid_lft forever preferred_lft forever

To activate the team interface, or to bring it “up”, issue a command as `root` in the following format:

	~]# **ip link set dev team0 up**

To temporarily deactivate the team interface, or to take it “down”, issue a command as `root` in the following format:

	~]# **ip link set dev team0 down**

To terminate, or kill, an instance of the team daemon, as `root` user, issue a command in the following format:

	~]# **teamd -t team0 -k**

The `-k` option is to specify that the instance of the daemon associated with the device team0 is to be killed. See the `teamd(8)` man page for other options.

For help on command-line options for `teamd`, issue the following command:

	~]$ **teamd -h**

In addition, see the `teamd(8)` man page.

### 5\.10.2. Creating a Network Team Using ifcfg Files	{#sec-Creating_a_Network_Team_Using_ifcfg_Files}

To create a networking team using `ifcfg` files, create a file in the `/etc/sysconfig/network-scripts/` directory as follows:

	DEVICE=team0
	DEVICETYPE=Team
	ONBOOT=yes
	BOOTPROTO=none
	IPADDR=192.168.11.1
	NETMASK=255.255.255.0
	TEAM_CONFIG='{"runner": {"name": "activebackup"}, "link_watch": {"name": "ethtool"}}'

This creates the interface to the team, in other words, this is the master.

To create a port to be a member of team0, create one or more files in the `/etc/sysconfig/network-scripts/` directory as follows:

	DEVICE=eth1
	HWADDR=D4:85:64:01:46:9E
	DEVICETYPE=TeamPort
	ONBOOT=yes
	TEAM_MASTER=team0
	TEAM_PORT_CONFIG='{"prio": 100}'

Add additional port interfaces similar to the above as required, changing the DEVICE and HWADDR field to match the ports (the network devices) being added. If port priority is not specified by `prio` it defaults to `0`; it accepts negative and positive values in the range `-32,767` to `+32,767`.

Specifying the hardware or MAC address using the **HWADDR** directive will influence the device naming procedure. This is explained in [Chapter 8, _Consistent Network Device Naming_](#ch-Consistent_Network_Device_Naming "Chapter 8. Consistent Network Device Naming").

To bring up the network team, issue the following command as `root`:

	~]# **ifup team0**

To view the network team, issue the following command:

	~]$ **ip link show**

### 5\.10.3. Add a Port to a Network Team Using iputils	{#sec-Add_a_port_to_a_Network_Team_Using_iputils}

To add a port em1 to a network team team0, using the ip utility, issue the following commands as `root`:

	~]# **ip link set dev em1 down**
	~]# **ip link set dev em1 master team0**

Add additional ports as required. Team driver will bring ports up automatically.

### 5\.10.4. Listing the ports of a Team Using teamnl	{#sec-Listing_the_ports_of_a_Team_Using_teamnl}

To view or list the ports in a network team, using the teamnl utility, issue the following command as `root`:

	~]# **teamnl team0 ports**
	em2: up 100 fullduplex
	em1: up 100 fullduplex

### 5\.10.5. Configuring Options of a Team Using teamnl	{#sec-Configuring_Options_of_a_Team_Using_teamnl}

To view or list all currently available options, using the teamnl utility, issue the following command as `root`:

	~]# **teamnl team0 options**

To configure a team to use active backup mode, issue the following command as `root`:

	~]# **teamnl team0 setoption mode activebackup**

### 5\.10.6. Add an Address to a Network Team Using iputils	{#sec-Add_an_address_to_a_Network_Team_Using_iputils}

To add an address to a team team0, using the ip utility, issue the following command as `root`:

	~]# **ip addr add 192.168.252.2/24 dev team0**

### 5\.10.7. Bring up an Interface to a Network Team Using iputils	{#sec-Bring_Up_an_interface_to_a_Network_Team_Using_iputils}

To activate or “bring up” an interface to a network team, team0, using the ip utility, issue the following command as `root`:

	~]# **ip link set team0 up**

### 5\.10.8. Viewing the Active Port Options of a Team Using teamnl	{#sec-Viewing_the_Active_Ports_of_a_Team_Using_teamnl}

To view or list the `activeport` option in a network team, using the teamnl utility, issue the following command as `root`:

	~]# **teamnl team0 getoption activeport**
	0

### 5\.10.9. Setting the Active Port Options of a Team Using teamnl	{#sec-Setting_the_Active_Ports_of_a_Team_Using_teamnl}

To set the `activeport` option in a network team, using the teamnl utility, issue the following command as `root`:

	~]# **teamnl team0 setoption activeport 5**

To check the change in team port options, issue the following command as `root`:

	~]# **teamnl team0 getoption activeport**
	5

## 5\.11. Controlling teamd with teamdctl	{#sec-Controlling_teamd_with_teamdctl}

In order to query a running instance of `teamd` for statistics or configuration information, or to make changes, the control tool teamdctl is used.

To view the current team state of a team team0, enter the following command as `root`:

	~]# **teamdctl team0 state view**

For a more verbose output:

	~]# **teamdctl team0 state view -v**

For a complete state dump in JSON format (useful for machine processing) of team0, use the following command:

	~]# **teamdctl team0 state dump**

For a configuration dump in JSON format of team0, use the following command:

	~]# **teamdctl team0 config dump**

To view the configuration of a port em1, that is part of a team team0, enter the following command:

	~]# **teamdctl team0 port config dump em1**

### 5\.11.1. Add a Port to a Network Team	{#sec-Add_a_port_to_a_Network_Team}

To add a port em1 to a network team team0, issue the following command as `root`:

	~]# **teamdctl team0 port add em1**

### 5\.11.2. Remove a Port From a Network Team	{#sec-Remove_a_Port_From_a_Network_Team}

To remove an interface em1 from a network team team0, issue the following command as `root`:

	~]# **teamdctl team0 port remove em1**

### 5\.11.3. Apply a Configuration to a Port in a Network Team	{#sec-Apply_a_Configuration_to_a_Port_in_a_Network_Team}

To apply a JSON format configuration to a port em1 in a network team team0, issue a command as `root` in the following format:

	~]# **teamdctl team0 port config update em1 _`JSON-config-string`_**

Where _`JSON-config-string`_ is the configuration as a string of text in JSON format. This will update the configuration of the port using the JSON format string supplied. An example of a valid JSON string for configuring a port would be the following:

	{
	  "prio": -10,
	  "sticky": true
	}

Use single quotes around the JSON configuration string and omit the line breaks.

Note that the old configuration will be overwritten and that any options omitted will be reset to the default values. See the `teamdctl(8)` man page for more team daemon control tool command examples.

### 5\.11.4. View the Configuration of a Port in a Network Team	{#sec-View_the_Configuration_of_a_Port_in_a_Network_Team}

To copy the configuration of a port em1 in a network team team0, issue the following command as `root`:

	~]# **teamdctl team0 port config dump em1**

This will dump the JSON format configuration of the port to standard output.

## 5\.12. Configure teamd Runners	{#sec-Configure_teamd_Runners}

Runners are units of code which are compiled into the Team daemon when an instance of the daemon is created. For an introduction to the `teamd` runners, see [Section 5.4, “Understanding the Network Teaming Daemon and the "Runners"”](#sec-Understanding_the_Network_Teaming_Daemon_and_the_Runners "5.4. Understanding the Network Teaming Daemon and the "Runners"").

### 5\.12.1. Configure the broadcast Runner	{#sec-Configure_the_broadcast_Runner}

To configure the broadcast runner, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	 "device": "team0",
	 "runner": {"name": "broadcast"},
	 "ports": {"em1": {}, "em2": {}}
	}

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.2. Configure the random Runner	{#sec-Configure_the_random_Runner}

The random runner behaves similarly to the roundrobin runner.

To configure the random runner, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	 "device": "team0",
	 "runner": {"name": "random"},
	 "ports": {"em1": {}, "em2": {}}
	}

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.3. Configure the roundrobin Runner	{#sec-Configure_the_roundrobin_Runner}

To configure the roundrobin runner, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	 "device": "team0",
	 "runner": {"name": "roundrobin"},
	 "ports": {"em1": {}, "em2": {}}
	}

A very basic configuration for roundrobin.

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.4. Configure the activebackup Runner	{#sec-Configure_the_activebackup_Runner}

The active backup runner can use all of the link-watchers to determine the status of links in a team. Any one of the following examples can be added to the team JSON format configuration file:

	{
	   "device": "team0",
	   "runner": {
	      "name": "activebackup"
	   },
	   "link_watch": {
	      "name": "ethtool"
	   },
	   "ports": {
	      "em1": {
	         "prio": -10,
	         "sticky": true
	      },
	      "em2": {
	         "prio": 100
	      }
	   }
	}

This example configuration uses the active-backup runner with ethtool as the link watcher. Port em2 has higher priority. The sticky flag ensures that if em1 becomes active, it stays active as long as the link remains up.

	{
	   "device": "team0",
	   "runner": {
	      "name": "activebackup"
	   },
	   "link_watch": {
	      "name": "ethtool"
	   },
	   "ports": {
	      "em1": {
	         "prio": -10,
	         "sticky": true,
	         "queue_id": 4
	      },
	      "em2": {
	         "prio": 100
	      }
	   }
	}

This example configuration adds a queue ID of `4`. It uses active-backup runner with ethtool as the link watcher. Port em2 has higher priority. But the sticky flag ensures that if em1 becomes active, it will stay active as long as the link remains up.

To configure the activebackup runner using ethtool as the link watcher and applying a delay, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	   "device": "team0",
	   "runner": {
	      "name": "activebackup"
	   },
	   "link_watch": {
	      "name": "ethtool",
	      "delay_up": 2500,
	      "delay_down": 1000
	   },
	   "ports": {
	      "em1": {
	         "prio": -10,
	         "sticky": true
	      },
	      "em2": {
	         "prio": 100
	      }
	   }
	}

This example configuration uses the active-backup runner with ethtool as the link watcher. Port em2 has higher priority. But the sticky flag ensures that if em1 becomes active, it stays active while the link remains up. Link changes are not propagated to the runner immediately, but delays are applied.

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.5. Configure the loadbalance Runner	{#sec-Configure_the_loadbalance_Runner}

This runner can be used for two types of load balancing, active and passive. In active mode, constant re-balancing of traffic is done by using statistics of recent traffic to share out traffic as evenly as possible. In static mode, streams of traffic are distributed randomly across the available links. This has a speed advantage due to lower processing overhead. In high volume traffic applications this is often preferred as traffic usually consists of multiple stream which will be distributed randomly between the available links, in his way load sharing is accomplished without intervention by `teamd`.

To configure the loadbalance runner for passive transmit (Tx) load balancing, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	 "device": "team0",
	 "runner": {
	   "name": "loadbalance",
	   "tx_hash": ["eth", "ipv4", "ipv6"]
	 },
	 "ports": {"em1": {}, "em2": {}}
	}

Configuration for hash-based passive transmit (Tx) load balancing.

To configure the loadbalance runner for active transmit (Tx) load balancing, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	   "device": "team0",
	   "runner": {
	     "name": "loadbalance",
	     "tx_hash": ["eth", "ipv4", "ipv6"],
	     "tx_balancer": {
	       "name": "basic"
	     }
	   },
	   "ports": {"em1": {}, "em2": {}}
	}

Configuration for active transmit (Tx) load balancing using basic load balancer.

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.6. Configure the LACP (802.3ad) Runner	{#sec-Configure_the_LACP_Runner}

To configure the LACP runner using ethtool as a link watcher, using an editor as `root`, add the following to the team JSON format configuration file:

	{
	   "device": "team0",
	   "runner": {
	       "name": "lacp",
	       "active": true,
	       "fast_rate": true,
	       "tx_hash": ["eth", "ipv4", "ipv6"]
	   },
	     "link_watch": {"name": "ethtool"},
	     "ports": {"em1": {}, "em2": {}}
	}

Configuration for connection to a _link aggregation control protocol_ (LACP) capable counterpart. The LACP runner should use ethtool to monitor the status of a link. It does not make sense to use any other link monitoring method besides the ethtool because, for example in the case of arp\_ping, the link would never come up. The reason is that the link has to be established first and only after that can packets, ARP included, go through. Using ethtool prevents this because it monitors each link layer individually.

Active load balancing is possible with this runner in the same way as it is done for the loadbalance runner. To enable active transmit (Tx) load balancing, add the following section:

	"tx_balancer": {
	       "name": "basic"
	}

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.7. Configure Monitoring of the Link State	{#sec-Configure_Monitoring_of_the_Link_State}

The following methods of link state monitoring are available. To implement one of the methods, add the JSON format string to the team JSON format configuration file using an editor running with `root` privileges.

#### 5\.12.7.1. Configure Ethtool for link-state Monitoring	{#sec-Configure_Ethtool_for_Link-state_Monitoring}

To add or edit an existing delay, in milliseconds, between the link coming up and the runner being notified about it, add or edit a section as follows:

	"link_watch": {
	       "name": "ethtool",
	       "delay_up": 2500
	}

To add or edit an existing delay, in milliseconds, between the link going down and the runner being notified about it, add or edit a section as follows:

	"link_watch": {
	       "name": "ethtool",
	       "delay_down": 1000
	}

#### 5\.12.7.2. Configure ARP Ping for Link-state Monitoring	{#sec-Configure_ARP_Ping_for_Link-state_Monitoring}

The team daemon `teamd` sends an ARP REQUEST to an address at the remote end of the link in order to determine if the link is up. The method used is the same as the arping utility but it does not use that utility.

Prepare a file containing the new configuration in JSON format similar to the following example:

	{
	       "device": "team0",
	       "runner": {"name": "activebackup"},
	       "link_watch":{
	           "name": "arp_ping",
	           "interval": 100,
	           "missed_max": 30,
	           "source_host": "192.168.23.2",
	           "target_host": "192.168.23.1"
	       },
	         "ports": {
	             "em1": {
	               "prio": -10,
	               "sticky": true
	             },
	             "em2": {
	               "prio": 100
	             }
	         }
	}

This configuration uses arp\_ping as the link watcher. The `missed_max` option is a limit value of the maximum allowed number of missed replies (ARP replies for example). It should be chosen in conjunction with the `interval` option in order to determine the total time before a link is reported as down.

To load a new configuration for a team port em2, from a file containing a JSON configuration, issue the following command as `root`:

	~]# port config update em2 _`JSON-config-file`_

Note that the old configuration will be overwritten and that any options omitted will be reset to the default values. See the `teamdctl(8)` man page for more team daemon control tool command examples.

#### 5\.12.7.3. Configure IPv6 NA/NS for Link-state Monitoring	{#sec-Configure_IPv6_NA_NS_for_Link-state_Monitoring}

	{
	  "device": "team0",
	    "runner": {"name": "activebackup"},
	    "link_watch": {
	    "name": "nsna_ping",
	    "interval": 200,
	    "missed_max": 15,
	    "target_host": "fe80::210:18ff:feaa:bbcc"
	    },
	      "ports": {
	        "em1": {
	          "prio": -10,
	          "sticky": true
	        },
	        "em2": {
	          "prio": 100
	        }
	      }
	}

To configure the interval between sending NS/NA packets, add or edit a section as follows:

	"link_watch": {
	    "name": "nsna_ping",
	    "interval": 200
	}

Value is positive number in milliseconds. It should be chosen in conjunction with the `missed_max` option in order to determine the total time before a link is reported as down.

To configure the maximum number of missed NS/NA reply packets to allow before reporting the link as down, add or edit a section as follows:

	"link_watch": {
	    "name": "nsna_ping",
	    "missed_max": 15
	}

Maximum number of missed NS/NA reply packets. If this number is exceeded, the link is reported as down. The `missed_max` option is a limit value of the maximum allowed number of missed replies (ARP replies for example). It should be chosen in conjunction with the `interval` option in order to determine the total time before a link is reported as down.

To configure the host name that is resolved to the `IPv6` address target address for the NS/NA packets, add or edit a section as follows:

	"link_watch": {
	    "name": "nsna_ping",
	    "target_host": "MyStorage"
	}

The “target\_host” option contains the host name to be converted to an `IPv6` address which will be used as the target address for the NS/NA packets. An `IPv6` address can be used in place of a host name.

Please see the `teamd.conf(5)` man page for more information.

### 5\.12.8. Configure Port Selection Override	{#sec-Configure_Port_Selection_Override}

The physical port which transmits a frame is normally selected by the kernel part of the team driver, and is not relevant to the user or system administrator. The output port is selected using the policies of the selected team mode (`teamd` runner). On occasion however, it is helpful to direct certain classes of outgoing traffic to certain physical interfaces to implement slightly more complex policies. By default the team driver is multiqueue aware and 16 queues are created when the driver initializes (see `/usr/share/doc/kernel-doc/Documentation/networking/multiqueue.txt` for details). If more or less queues are desired, the Netlink attribute **tx\_queues** can be used to change this value during the team driver instance creation.

The queue ID for a port can be set by the port configuration option `queue_id` as follows:

	{
	  "queue_id": 3
	}

These queue ID's can be used in conjunction with the tc utility to configure a multiqueue queue discipline and filters to bias certain traffic to be transmitted on certain port devices. For example, if using the above configuration and wanting to force all traffic bound to `192.168.1.100` to use eth1 in the team as its output device, issue commands as `root` in the following format:

	~]# **tc qdisc add dev team0 handle 1 root multiq**
	~]# **tc filter add dev team0 protocol ip parent 1: prio 1 u32 match ip dst \**
	** 192.168.1.100 action skbedit queue_mapping 3**

This mechanism of overriding runner selection logic in order to bind traffic to a specific port can be used with all runners.

### 5\.12.9. Configure BPF-based Tx Port Selectors	{#sec-Configure_BPF-based_Tx_Port_Selectors_for_Hash_Computation_Algorithm}

The loadbalance and LACP runners uses hashes of packets to sort network traffic flow. The hash computation mechanism is based on the _Berkeley Packet Filter_ (BPF) code. The BPF code is used to generate a hash rather than make a policy decision for outgoing packets. The hash length is 8 bits giving 256 variants. This means many different _socket buffers_ (SKB) can have the same hash and therefore pass traffic over the same link. The use of a short hash is a quick way to sort traffic into different streams for the purposes of load balancing across multiple links. In static mode, the hash is only used to decide out of which port the traffic should be sent. In active mode, the runner will continually reassign hashes to different ports in an attempt to reach a perfect balance.

The following fragment types or strings can be used for packet Tx hash computation:

* `eth` — Uses source and destination MAC addresses.

* `vlan` — Uses VLAN ID.

* `ipv4` — Uses source and destination `IPv4` addresses.

* `ipv6` — Uses source and destination `IPv6` addresses.

* `ip` — Uses source and destination `IPv4` and `IPv6` addresses.

* `l3` — Uses source and destination `IPv4` and `IPv6` addresses.

* `tcp` — Uses source and destination `TCP` ports.

* `udp` — Uses source and destination `UDP` ports.

* `sctp` — Uses source and destination `SCTP` ports.

* `l4` — Uses source and destination `TCP` and `UDP` and `SCTP` ports.

These strings can be used by adding a line in the following format to the load balance runner:

	"tx_hash": ["eth", "ipv4", "ipv6"]

See [Section 5.12.5, “Configure the loadbalance Runner”](#sec-Configure_the_loadbalance_Runner "5.12.5. Configure the loadbalance Runner") for an example.

## 5\.13. Configure Network Teaming Using nmcli	{#sec-Configure_Network_Teaming_Using_nmcli}

To create a new team interface, with name team-ServerA, issue a command as follows:

	~]$ **nmcli connection add type team ifname ServerA**
	Connection 'team-ServerA' (981eb129-1707-4a2e-a6ea-413330d96c10) successfully added.

As no JSON configuration file was specified the default configuration is used. Notice that the name was derived from the interface name by prepending the type. Alternatively, specify a name with `con-name` as follows:

	~]$ **nmcli connection add type team con-name Team0 ifname ServerB**
	Connection 'Team0' (fcafb3f0-4c95-48df-9e28-7ac7213f38ba) successfully added.

To view the team interfaces just configured, issue a command as follows:

	~]$ **nmcli connection show**
	NAME              UUID                                  TYPE        TIMESTAMP-REAL
	Team0             fcafb3f0-4c95-48df-9e28-7ac7213f38ba  team        never
	team-ServerA      981eb129-1707-4a2e-a6ea-413330d96c10  team        never

To load a team configuration file for a team that already exists, issue a command as follows:

	~]$ **nmcli connection modify team-ServerA team.config _`JSON-config`_**

You can specify the team configuration either as JSON string or provide a file name containing the configuration. The file name can include the path. In both cases, what is stored in the _`team.config`_ property is the JSON string. In the case of a JSON string, use single quotes around the string and paste the entire string to the command line.

To review the _`team.config`_ property, enter a command as follows:

	~]$ **nmcli conn show team-ServerA | grep team.config**

To add an interface to the team, with name team-slave-ens3, issue a command as follows:

	~]$ **nmcli connection add type team-slave ifname ens3 master Team0**
	Connection 'team-slave-ens3' (a33d5d32-87d7-4dc4-8a27-5a44aabfa440) successfully added.

Notice that the name was derived from the interface name by prepending the type. Alternatively, specify a name with `con-name` as follows:

	~]$ **nmcli con add type team-slave con-name Team0-port1 ifname ens3 master Team0**
	Connection 'Team0-port1' (adbf21f2-51b6-492f-8fc8-48b831383ac9) successfully added.
	~]$ **nmcli con add type team-slave con-name Team0-port2 ifname ens7 master Team0**
	Connection 'Team0-port2' (e5317075-c0c1-472f-b25d-0433b0297ea3) successfully added.

At time of writing, nmcli only supports Ethernet ports.

In order to bring up a team, the ports must be brought up first as follows:

	~]$ **nmcli connection up Team0-port1**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/2)

	~]$ **nmcli connection up Team0-port2**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/3)

You can verify the team interface was brought up by the activation of the ports, as follows:

	~]$ **ip link**
	3:  Team0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue state UP mode DEFAULT
	    link/ether 52:54:00:76:6f:f0 brd ff:ff:ff:ff:ff:f

Alternatively, issue a command to bring up the team as follows:

	~]$ **nmcli connection up Team0**
	Connection successfully activated (D-Bus active path: /org/freedesktop/NetworkManager/ActiveConnection/4)

See [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli") for an introduction to nmcli

## 5\.14. Additional Resources	{#sec-Network_Teaming-additional_resources}

The following sources of information provide additional resources regarding network teaming.

### 5\.14.1. Installed Documentation	{#sec-teamd-docs-inst}

* `teamd(8)` man page — Describes the `teamd` service.

* `teamdctl(8)` man page — Describes the `teamd` control tool.

* `teamd.conf(5)` man page — Describes the `teamd` configuration file.

* `teamnl(8)` man page — Describes the `teamd` Netlink library.

* `bond2team(1)` man page — Describes a tool to convert bonding options to team.

### 5\.14.2. Installable Documentation	{#sec-Configure_teamd-docs-installable}

* ``/usr/share/doc/kernel-doc-_`<kernel_version>`_/Documentation/`` — This directory, which is provided by the kernel-doc package, contains information on bonding which is also relevant to teaming. Before accessing the kernel documentation, you must run the following command as `root`:

	~]# **yum install kernel-doc**

    `/usr/share/doc/kernel-doc/Documentation/networking/multiqueue.txt` — Describes kernel support for multiqueue devices.

### 5\.14.3. Online Documentation	{#sec-teamd_docs-online}

<http://www.libteam.org>
:    The upstream project.

[http://www.w3schools.com/json/json\_syntax.asp](http://www.w3schools.com/json/json_syntax.asp)
:    An explanation of JSON syntax.

## Chapter 6. Configure Network Bridging	{#ch-Configure_Network_Bridging}

A network bridge is a link-layer device which forwards traffic between networks based on MAC addresses. It makes forwarding decisions based on a table of MAC addresses which it builds by listening to network traffic and thereby learning what hosts are connected to each network. A software bridge can be used within a Linux host in order to emulate a hardware bridge, for example in virtualization applications for sharing a NIC with one or more virtual NICs.

Note that a bridge cannot be established over Wi-Fi networks operating in _Ad-Hoc_ or _Infrastructure_ modes. This is due to the IEEE 802.11 standard that specifies the use of 3-address frames in Wi-Fi for the efficient use of airtime. A system configured to be an _access point_ (AP) running the `hostapd` can support the necessary 4-address frames.

## 6\.1. Using NetworkManager	{#sec-Network_Bridging_Using_NetworkManager}

When starting a bridge interface, NetworkManager waits for at least one port to enter the “forwarding” state before beginning any network-dependent `IP` configuration such as `DHCP` or `IPv6` autoconfiguration. Static `IP` addressing is allowed to proceed before any slaves or ports are connected or begin forwarding packets.

### 6\.1.1. Establishing a Bridge Connection	{#sec-Establishing_a_Bridge_Connection}

Procedure 6.1. Adding a New Bridge Connection

1. You can configure a new Bridge connection by opening the Network window and selecting the plus symbol below the menu.

1. To use the graphical Network settings tool, press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the plus symbol below the menu. The Add Network Connection window appears.

1. Select the Bridge menu entry. The Editing Bridge connection _`1`_ window appears.

Procedure 6.2. Editing an Existing Bridge Connection

You can configure an existing bridge connection by opening the Network window and selecting the name of the connection from the list. Then click the Edit button.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the Bridge connection you wish to edit from the left hand menu.

1. Click the Options button.

#### Configuring the Connection Name, Auto-Connect Behavior, and Availability Settings	{#bh-Configuring_the_Connection_Name_Auto-Connect_Behavior_and_Availability_Settings-bridge}

Five settings in the Editing dialog are common to all connection types, see the General tab:

* Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the menu of the Network window.

* Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. See [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

* All users may connect to this network — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. See [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details. To prevent unexpected behavior during installation, ensure that this check box remains selected for any network interface that you configure.

* Automatically connect to VPN when using this connection — Select this box if you want NetworkManager to auto-connect to a VPN connection when it is available. Select the VPN from the dropdown menu.

* Firewall Zone — Select the Firewall Zone from the dropdown menu.

#### Configuring the Bridge Tab	{#bh-Configuring_the_Bridge_Tab}

Interface name
:    The name of the interface to the bridge.

Bridged connections
:    One or more slave interfaces.

Aging time
:    The time, in seconds, a MAC address is kept in the MAC address forwarding database.

Enable STP (Spanning Tree Protocol)
:    If required, select the check box to enable `STP`.

Priority
:    The bridge priority; the bridge with the lowest priority will be elected as the root bridge.

Forward delay
:    The time, in seconds, spent in both the Listening and Learning states before entering the Forwarding state.

Hello time
:    The time interval, in seconds, between sending configuration information in bridge protocol data units (BPDU).

Max age
:    The maximum time, in seconds, to store the configuration information from BPDUs. This value should be twice the Hello Time plus 1 but less than twice the Forwarding delay minus 1.

Figure 6.1. Editing Bridge Connection 1

![Editing Bridge Connection 1][3]

<br />
[[D](ld-mediaobj-Editing-Bridge-Connection-1_Gnome3.png.html)]

<br />

Procedure 6.3. Adding a Slave Interface to a Bridge

1. To add a port to a bridge, select the Bridge tab in the Editing Bridge connection _`1`_ window. If necessary, open this window by following the procedure in [Procedure 6.2, “Editing an Existing Bridge Connection”](#procedure-Editing_an_Existing_Bridge_Connection "Procedure 6.2. Editing an Existing Bridge Connection").

1. Click Add. The Choose a Connection Type menu appears.

1. Select the type of connection to be created from the list. Click Create. A window appropriate to the connection type selected appears.

1. Select the Bridge Port tab. Configure Priority and Path cost as required. Note the STP priority for a bridge port is limited by the Linux kernel. Although the standard allows a range of `0` to `255`, Linux only allows `0` to `63`. The default is `32` in this case.

1. If required, select the Hairpin mode check box to enable forwarding of frames for external processing. Also known as _virtual Ethernet port aggregator_ (VEPA) mode.

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-bridge}

Once you have finished editing your new bridge connection, click the Save button to save your customized configuration. To make NetworkManager apply the changes, power cycle the interface. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking Configure to return to the Editing dialog.

Then, to configure:

* `IPv4` settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings"), or;

* `IPv6` settings for the connection, click the IPv6 Settings tab and proceed to [Section 2.2.10.5, “Configuring IPv6 Settings”](#sec-Configuring_IPv6_Settings "2.2.10.5. Configuring IPv6 Settings").

## 6\.2. Using the Command Line Interface (CLI)	{#sec-Network_Bridging_Using_the_Command_Line_Interface}

### 6\.2.1. Check if Bridging Kernel Module is Installed	{#sec-Check_if_Bridging_Kernel_Module_is_Installed}

In Fedora, the bridging module is loaded by default. If necessary, you can make sure that the module is loaded by issuing the following command as `root`:

	~]# **modprobe --first-time bridge**
	modprobe: ERROR: could not insert 'bridge': Module already in kernel

To display information about the module, issue the following command:

	~]$ **modinfo bridge**

See the `modprobe(8)` man page for more command options.

### 6\.2.2. Create a Network Bridge	{#sec-Create_a_Network_Bridge}

To create a network bridge, create a file in the `/etc/sysconfig/network-scripts/` directory called ``ifcfg-br_`N`_``, replacing _`N`_ with the number for the interface, such as `0`.

The contents of the file is similar to whatever type of interface is getting bridged to, such as an Ethernet interface. The differences in this example are as follows:

* The `DEVICE` directive is given an interface name as its argument in the format ``br_`N`_``, where _`N`_ is replaced with the number of the interface.

* The `TYPE` directive is given an argument `Bridge` or `Ethernet`. This directive determines the device type and the argument is case sensitive.

* The bridge interface configuration file is given an `IP` address whereas the physical interface configuration file must only have a MAC address (see below).

* An extra directive, `DELAY=0`, is added to prevent the bridge from waiting while it monitors traffic, learns where hosts are located, and builds a table of MAC addresses on which to base its filtering decisions. The default delay of 30 seconds is not needed if no routing loops are possible.

* The `NM_CONTROLLED=no` should be added to the Ethernet interface to prevent NetworkManager from altering the file. It can also be added to the bridge configuration file.

The following is a sample bridge interface configuration file using a static `IP` address:

Example 6.1. Sample ifcfg-br0 Interface Configuration File

	DEVICE=br0
	TYPE=Bridge
	IPADDR=192.168.1.1
	NETMASK=255.255.255.0
	ONBOOT=yes
	BOOTPROTO=none
	NM_CONTROLLED=no
	DELAY=0

<br />

To complete the bridge another interface is created, or an existing interface is modified, and pointed to the bridge interface. The following is a sample Ethernet interface configuration file pointing to a bridge interface. Configure your physical interface in ``/etc/sysconfig/network-scripts/ifcfg-eth_`X`_``, where _`X`_ is a unique number corresponding to a specific interface, as follows:

Example 6.2. Sample ifcfg-ethX Interface Configuration File

	DEVICE=ethX
	TYPE=Ethernet
	HWADDR=AA:BB:CC:DD:EE:FF
	BOOTPROTO=none
	ONBOOT=yes
	NM_CONTROLLED=no
	BRIDGE=br0

<br />

### Note

For the `DEVICE` directive, almost any interface name could be used as it does not determine the device type. `TYPE=Ethernet` is not strictly required. If the `TYPE` directive is not set, the device is treated as an Ethernet device (unless it's name explicitly matches a different interface configuration file.)

Specifying the hardware or MAC address using the **HWADDR** directive will influence the device naming procedure as explained in [Chapter 8, _Consistent Network Device Naming_](#ch-Consistent_Network_Device_Naming "Chapter 8. Consistent Network Device Naming").

See the _Fedora 20 System Administrator's Reference Guide_ for a review of the directives and options used in network interface configuration files.

### Warning

If you are configuring bridging on a remote host, and you are connected to that host over the physical NIC you are configuring, please consider the implications of losing connectivity before proceeding. You will lose connectivity when restarting the service and may not be able to regain connectivity if any errors have been made. Console, or out-of-band access is advised.

Restart the networking service in order for the changes to take effect. As `root` issue the following command:

	~]# **systemctl network restart**

An example of a network bridge formed from two or more bonded Ethernet interfaces will now be given as this is another common application in a virtualization environment. If you are not very familiar with the configuration files for bonded interfaces then please refer to [Section 4.3.2, “Create a Channel Bonding Interface”](#sec-Create_a_Channel_Bonding_Interface "4.3.2. Create a Channel Bonding Interface")

Create or edit two or more Ethernet interface configuration files, which are to be bonded, as follows:

	DEVICE=ethX
	TYPE=Ethernet
	SLAVE=yes
	MASTER=bond0
	BOOTPROTO=none
	HWADDR=AA:BB:CC:DD:EE:FF
	NM_CONTROLLED=no

### Note

Using ``eth_`X`_`` as the interface name is common practice but almost any name could be used.

Create or edit one interface configuration file, `/etc/sysconfig/network-scripts/ifcfg-bond0`, as follows:

	DEVICE=bond0
	ONBOOT=yes
	BONDING_OPTS='mode=1 miimon=100'
	BRIDGE=brbond0
	NM_CONTROLLED=no

For further instructions and advice on configuring the bonding module and to view the list of bonding parameters, see the _Fedora 20 System Administrator's Reference Guide_.

Create or edit one interface configuration file, `/etc/sysconfig/network-scripts/ifcfg-brbond0`, as follows:

	DEVICE=brbond0
	ONBOOT=yes
	TYPE=Bridge
	IPADDR=192.168.1.1
	NETMASK=255.255.255.0
	NM_CONTROLLED=no

We now have two or more interface configuration files with the `MASTER=bond0` directive. These point to the configuration file named `/etc/sysconfig/network-scripts/ifcfg-bond0`, which contains the `DEVICE=bond0` directive. This `ifcfg-bond0` in turn points to the `/etc/sysconfig/network-scripts/ifcfg-brbond0` configuration file, which contains the `IP` address, and acts as an interface to the virtual networks inside the host.

Restart the networking service, in order for the changes to take effect. As `root` issue the following command:

	~]# **systemctl network restart**

## 6\.3. Using the NetworkManager Command Line Tool, nmcli	{#sec-Network_Bridging_sec-Using_the_NetworkManager_Command_Line_Tool_nmcli}

To create a bridge, with name bridge-br0, issue a command as follows:

	~]$ **nmcli con add type bridge ifname br0**
	Connection 'bridge-br0' (79cf6a3e-0310-4a78-b759-bda1cc3eef8d) successfully added.

If no interface name is specified, the name will default to bridge, bridge-1, bridge-2, and so on.

To view the connections, issue the following command:

	~]$ **nmcli con show conf**
	NAME        UUID                                 TYPE           TIMESTAMP-REAL
	eth0        4d5c449a-a6c5-451c-8206-3c9a4ec88bca 802-3-ethernet Mon 21 Oct 2013 16:01:53 BST
	bridge-br0  79cf6a3e-0310-4a78-b759-bda1cc3eef8d bridge         never

_Spanning tree protocol_ (STP) according to the IEEE 802.1D standard is enabled by default. To disable `STP` for this bridge, issue a command as follows:

	~]$ **nmcli con bridge-br0 stp no**

To re-enable `802.1D STP` for this bridge, issue a command as follows:

	~]$ **nmcli con bridge-br0 stp yes**

The default bridge priority for `802.1D STP` is `32768`. The lower number is preferred in root bridge selection. For example, a bridge with priority of `28672` would be selected as the root bridge in preference to a bridge with priority value of `32768` (the default). To create a bridge with a non-default value, issue a command as follows:

	~]$ **nmcli con add type bridge ifname br5 stp yes priority 28672**
	Connection 'bridge-br5' (86b83ad3-b466-4795-aeb6-4a66eb1856c7) successfully added.

The allowed values are in the range `0` to `65535`, but can only be set in multiples of `4096`.

To change the bridge priority of an existing bridge to a non-default value, issue a command in the following format:

	~]$ **nmcli connection modify bridge-br5 bridge.priority 36864**

The allowed values are in the range `0` to `65535`, but can only be set in multiples of `4096`.

Further options for `802.1D STP` are listed in the bridge section of the `nmcli(1)` man page.

To add, or enslave an interface, for example eth1, to the bridge bridge-br0, issue a command as follows:

	~]$ **nmcli con add type bridge-slave ifname eth1 master bridge-br0**
	Connection 'bridge-slave-eth1' (70ffae80-7428-4d9c-8cbd-2e35de72476e) successfully added.

At time of writing, nmcli only supports Ethernet slaves.

To change a value using interactive mode, issue the following command:

	~]$ **nmcli connection edit bridge-br0**

You will be placed at the nmcli prompt.

	nmcli&gt; **set bridge.priority 4096**
	nmcli&gt; **save**
	Connection 'bridge-br0' (79cf6a3e-0310-4a78-b759-bda1cc3eef8d) successfully saved.
	nmcli&gt; **quit**

See [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli") for an introduction to nmcli

## 6\.4. Additional Resources	{#sec-Network_Bridging-additional_resources}

The following sources of information provide additional resources regarding network bridging.

### 6\.4.1. Installed Documentation	{#sec-Network_Bridging-docs-inst}

* `nmcli(1)` man page — Describes NetworkManager's command‐line tool.

* `nmcli-examples(5)` man page — Gives examples of nmcli commands.

* `nm-settings(5)` man page — Description of settings and parameters of NetworkManager connections.

## Chapter 7. Configure 802.1Q VLAN tagging	{#ch-Configure_802_1Q_VLAN_Tagging}

## 7\.1. Configure 802.1Q VLAN Tagging Using a GUI	{#sec-Configure_802_1Q_VLAN_Tagging_Using_a_GUI}

### 7\.1.1. Establishing a VLAN Connection	{#sec-Establishing_a_VLAN_Connection}

You can use the GNOME control-center utility to direct NetworkManager to create a VLAN using an existing interface as the parent interface. At time of writing, you can only make VLANs on Ethernet devices. Note that VLAN devices are only created automatically if the parent interface is set to connect automatically.

Procedure 7.1. Adding a New VLAN Connection

You can configure a VLAN connection by opening the Network window, clicking the plus symbol, and selecting VLAN from the list.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Click the plus symbol to open the selection list. Select VLAN. The Editing VLAN Connection _`1`_ window appears.

1. On the VLAN tab, select the parent interface from the drop-down list you want to use for the VLAN connection.

1. Enter the VLAN ID

1. Enter a VLAN interface name. This is the name of the VLAN interface that will be created. For example, `eth0.1` or `vlan2`. (Normally this is either the parent interface name plus “`.`” and the VLAN ID, or “`vlan`” plus the VLAN ID.)

1. Review and confirm the settings and then click the Save button.

1. To edit the VLAN-specific settings see [Section 7.1.1.1, “Configuring the VLAN Tab”](#sec-Configuring_the_VLAN_Tab "7.1.1.1. Configuring the VLAN Tab").

Procedure 7.2. Editing an Existing VLAN Connection

Follow these steps to edit an existing VLAN connection.

1. Press the **Super** key to enter the Activities Overview, type **control network** and then press **Enter**. The Network settings tool appears.

1. Select the connection you wish to edit and click the Options button.

1. Select the General tab.

1. Configure the connection name, auto-connect behavior, and availability settings.

    These settings in the Editing dialog are common to all connection types:

  * Connection name — Enter a descriptive name for your network connection. This name will be used to list this connection in the VLAN section of the Network window.

  * Automatically connect to this network when it is available — Select this box if you want NetworkManager to auto-connect to this connection when it is available. Refer to [Section 2.2.3, “Connecting to a Network Automatically”](#sec-Connecting_to_a_Network_Automatically "2.2.3. Connecting to a Network Automatically") for more information.

  * Available to all users — Select this box to create a connection available to all users on the system. Changing this setting may require root privileges. Refer to [Section 2.2.4, “System-wide and Private Connection Profiles”](#sec-System-wide_and_Private_Connection_Profiles "2.2.4. System-wide and Private Connection Profiles") for details.

1. To edit the VLAN-specific settings see [Section 7.1.1.1, “Configuring the VLAN Tab”](#sec-Configuring_the_VLAN_Tab "7.1.1.1. Configuring the VLAN Tab").

#### Saving Your New (or Modified) Connection and Making Further Configurations	{#bh-Saving_Your_New_or_Modified_Connection_and_Making_Further_Configurations-VLAN}

Once you have finished editing your VLAN connection, click the Save button to save your customized configuration. To make NetworkManager apply the changes, power cycle the interface. See [Section 2.2.1, “Connecting to a Network Using a GUI”](#sec-Connecting_to_a_Network_Using_a_GUI "2.2.1. Connecting to a Network Using a GUI") for information on using your new or altered connection.

You can further configure an existing connection by selecting it in the Network window and clicking Options to return to the Editing dialog.

Then, to configure:

* IPv4 settings for the connection, click the IPv4 Settings tab and proceed to [Section 2.2.10.4, “Configuring IPv4 Settings”](#sec-Configuring_IPv4_Settings "2.2.10.4. Configuring IPv4 Settings").

#### 7\.1.1.1. Configuring the VLAN Tab	{#sec-Configuring_the_VLAN_Tab}

If you have already added a new VLAN connection (refer to [Procedure 7.1, “Adding a New VLAN Connection”](#procedure-Adding_a_New_VLAN_Connection "Procedure 7.1. Adding a New VLAN Connection") for instructions), you can edit the VLAN tab to set the parent interface and the VLAN ID.

Parent Interface
:    A previously configured interface can be selected in the drop-down list.

VLAN ID
:    The identification number to be used to tag the VLAN network traffic.

VLAN interface name
:    The name of the VLAN interface that will be created. For example, `eth0.1` or `vlan2`.

Cloned MAC address
:    Optionally sets an alternate MAC address to use for identifying the VLAN interface. This can be used to change the source MAC address for packets sent on this VLAN.

MTU
:    Optionally sets a Maximum Transmission Unit (MTU) size to be used for packets to be sent over the VLAN connection.

## 7\.2. Configure 802.1Q VLAN Tagging Using the Command Line	{#sec-Configure_802_1Q_VLAN_Tagging_Using_the_Command_Line}

In Fedora, the `8021q` module is loaded by default. If necessary, you can make sure that the module is loaded by issuing the following command as `root`:

	~]# **modprobe --first-time 8021q**
	modprobe: ERROR: could not insert '8021q': Module already in kernel

To display information about the module, issue the following command:

	~]$ **modinfo 8021q**

See the `modprobe(8)` man page for more command options.

### 7\.2.1. Setting Up 802.1Q VLAN Tagging Using ifcfg Files	{#sec-Setting_Up_802.1Q_VLAN_Tagging_Using_ifcfg_Files}

1. Configure your physical interface in ``/etc/sysconfig/network-scripts/ifcfg-eth_`X`_``, where _`X`_ is a unique number corresponding to a specific interface, as follows:

	DEVICE=ethX
	TYPE=Ethernet
	BOOTPROTO=none
	ONBOOT=yes

1. Configure the VLAN interface configuration in the `/etc/sysconfig/network-scripts/` directory. The configuration file name should be the physical interface plus a `.` character plus the VLAN ID number. For example, if the VLAN ID is 192, and the physical interface is _`eth0`_, then the configuration file name should be `ifcfg-eth0.192`:

	DEVICE=ethX.192
	BOOTPROTO=none
	ONBOOT=yes
	IPADDR=192.168.1.1
	NETMASK=255.255.255.0
	NETWORK=192.168.1.0
	VLAN=yes

    If there is a need to configure a second VLAN, with for example, VLAN ID 193, on the same interface, _`eth0`_, add a new file with the name `eth0.193` with the VLAN configuration details.

1. Restart the networking service in order for the changes to take effect. As `root` issue the following command:

	~]# **systemctl restart network**

## 7\.3. Configure 802.1Q VLAN Tagging Using ip Commands	{#sec-Configure_802_1Q_VLAN_Tagging_ip_Commands}

To create an 802.1Q VLAN interface on Ethernet interface _`eth0`_, with name _`VLAN8`_ and ID `8`, issue a command as `root` as follows:

	~]# **ip link add link _`eth0`_ name _`eth0.8`_ type vlan id 8**

To view the VLAN, issue the following command:

	~]$ **ip -d link show _`eth0.8`_**
	4: eth0.8@eth0: &lt;BROADCAST,MULTICAST,UP,LOWER_UP&gt; mtu 1500 qdisc noqueue state UP mode DEFAULT
	     link/ether 52:54:00:ce:5f:6c brd ff:ff:ff:ff:ff:ff promiscuity 0
	     vlan protocol 802.1Q id 8 &lt;REORDER_HDR&gt;

Note that the ip utility interprets the VLAN ID as a hexadecimal value if it is preceded by `0x` and as an octal value if it has a leading `0`. This means that in order to assign a VLAN ID with a decimal value of `22`, you must not add any leading zeros.

To remove the VLAN, issue a command as `root` as follows:

	~]# **ip link delete _`eth0.8`_**

### Note

VLAN interfaces created using ip commands on the command line will be lost if the system is shutdown or restarted. To configure VLAN interfaces to be persistent after a system restart, use `ifcfg` files. See [Section 7.2.1, “Setting Up 802.1Q VLAN Tagging Using ifcfg Files”](#sec-Setting_Up_802.1Q_VLAN_Tagging_Using_ifcfg_Files "7.2.1. Setting Up 802.1Q VLAN Tagging Using ifcfg Files")

## 7\.4. Configure 802.1Q VLAN Tagging Using the Command Line Tool, nmcli	{#sec-Configure_802_1Q_VLAN_Tagging_Using_the_Command_Line_Tool_nmcli}

To create an 802.1Q VLAN interface on Ethernet interface _`eth0`_, with VLAN interface _`VLAN10`_ and ID `10`, issue a command as follows:

	~]$ **nmcli con add type vlan ifname _`VLAN10`_ dev _`eth0`_ id 10**
	Connection 'vlan-VLAN10' (37750b4a-8ef5-40e6-be9b-4fb21a4b6d17) successfully added.

Note that as no `con-name` was given for the VLAN interface, the name was derived from the interface name by prepending the type. Alternatively, specify a name with `con-name` as follows:

	~]$ **nmcli con add type vlan con-name _`VLAN12`_ dev _`eth0`_ id 12**
	Connection 'VLAN12' (b796c16a-9f5f-441c-835c-f594d40e6533) successfully added.

Further options for the VLAN command are listed in the VLAN section of the `nmcli(1)` man page. In the man pages the device on which the VLAN is created is referred to as the parent device. In the example above the device was specified by its interface name, eth0, it can also be specified by the connection UUID or MAC address.

To create an 802.1Q VLAN connection profile with ingress priority mapping on Ethernet interface _`eth1`_, with name VLAN1 and ID `13`, issue a command as follows:

	~]$ **nmcli con add type vlan con-name _`VLAN1`_ dev _`eth2`_ id 13 ingress "2:3,3:5"**

To view all the parameters associated with the VLAN created above, issue a command as follows:

	~]$ **nmcli connection show _`vlan-VLAN10`_**

To change the MTU, issue a command as follows:

	~]$ **nmcli connection modify _`vlan-VLAN10`_ 802.mtu 1496**

The MTU setting determines the maximum size of the network layer packet. The maximum size of the payload the link-layer frame can carry in turn limits the network layer MTU. For standard Ethernet frames this means an MTU of 1500 bytes. It should not be necessary to change the MTU when setting up a VLAN as the link-layer header is increased in size by 4 bytes to accommodate the 802.1Q tag.

At time of writing, `connection.interface-name` and `vlan.interface-name` have to be the same (if they are set). They must therefore be changed simultaneously using nmcli's interactive mode. To change a VLAN connections name, issue commands as follows:

	~]$ **nmcli con edit _`vlan-VLAN10`_**
	nmcli&gt; **set vlan.interface-name _`superVLAN`_**
	nmcli&gt; **set connection.interface-name _`superVLAN`_**
	nmcli&gt; **save**
	nmcli&gt; **quit**

The nmcli utility can be used to set and clear `ioctl` flags which change the way the 802.1Q code functions. The following VLAN flags are supported by NetworkManager:

* 0x01 - reordering of output packet headers

* 0x02 - use GVRP protocol

* 0x04 - loose binding of the interface and its master

The state of the VLAN is synchronized to the state of the parent or master interface (the interface or device on which the VLAN is created). If the parent interface is set to the “down” administrative state then all associated VLANs are set down and all routes are flushed from the routing table. Flag `0x04` enables a _loose binding_ mode, in which only the operational state is passed from the parent to the associated VLANs, but the VLAN device state is not changed.

To set a VLAN flag, issue a command as follows:

	~]$ **nmcli connection modify vlan-VLAN10 vlan.flags 1**

See [Section 2.4, “Using the NetworkManager Command Line Tool, nmcli”](#sec-Using_the_NetworkManager_Command_Line_Tool_nmcli "2.4. Using the NetworkManager Command Line Tool, nmcli") for an introduction to nmcli

## 7\.5. Additional Resources	{#sec-Configure_802_1Q_VLAN_Tagging-additional_resources}

The following sources of information provide additional resources regarding Network Teaming.

### 7\.5.1. Installed Documentation	{#sec-Configure_802_1Q_VLAN_Tagging-docs-inst}

* `ip-link(8)` man page — Describes the ip utility's network device configuration commands.

* `nmcli(1)` man page — Describes NetworkManager's command‐line tool.

* `nmcli-examples(5)` man page — Gives examples of nmcli commands.

* `nm-settings(5)` man page — Description of settings and parameters of NetworkManager connections.

## Chapter 8. Consistent Network Device Naming	{#ch-Consistent_Network_Device_Naming}

Fedora 20 provides methods for consistent and predictable network device naming for network interfaces. These features change the name of network interfaces on a system in order to make locating and differentiating the interfaces easier.

Traditionally, network interfaces in Linux are enumerated as `eth[0123…]`, but these names do not necessarily correspond to actual labels on the chassis. Modern server platforms with multiple network adapters can encounter non-deterministic and counter-intuitive naming of these interfaces. This affects both network adapters embedded on the motherboard (_Lan-on-Motherboard_, or _LOM_) and add-in (single and multiport) adapters.

In Fedora 20, `systemd` and udev support a number of different naming schemes. The default is to assign fixed names based on firmware, topology, and location information. This has the advantage that the names are fully automatic, fully predictable, that they stay fixed even if hardware is added or removed (no re-enumeration takes place), and that broken hardware can be replaced seamlessly. The disadvantage is that they are sometimes harder to read than the eth0 or wlan0 names traditionally used. For example: enp5s0.

## 8\.1. Naming Schemes Hierarchy	{#sec-Naming_Schemes_Hierarchy}

By default, `systemd` will name interfaces using the following policy to apply the supported naming schemes:

* **Scheme 1:** Names incorporating Firmware or BIOS provided index numbers for on-board devices (example: `eno1`), are applied if that information from the firmware or BIOS is applicable and available, else falling back to scheme 2.

* **Scheme 2:** Names incorporating Firmware or BIOS provided PCI Express hotplug slot index numbers (example: `ens1`) are applied if that information from the firmware or BIOS is applicable and available, else falling back to scheme 3.

* **Scheme 3:** Names incorporating physical location of the connector of the hardware (example: `enp2s0`), are applied if applicable, else falling directly back to scheme 5 in all other cases.

* **Scheme 4:** Names incorporating interface's MAC address (example: `enx78e7d1ea46da`), is not used by default, but is available if the user chooses.

* **Scheme 5:** The traditional unpredictable kernel naming scheme, is used if all other methods fail (example: `eth0`).

This policy, the procedure outlined above, is the default. If the system has biosdevname enabled, it will be used. Note that enabling biosdevname requires passing **biosdevname=1** as a command line parameter except in the case of a Dell system, where biosdevname will be used by default as long as it is installed. If the user has added udev rules which change the name of the kernel devices, those rules will take precedence.

## 8\.2. Understanding the Device Renaming Procedure	{#sec-Understanding_the_Device_Renaming_Procedure}

The device name procedure in detail is as follows:

1. A rule in `/usr/lib/udev/rules.d/60-net.rules` instructs the udev helper utility, /lib/udev/rename\_device, to look into all ``/etc/sysconfig/network-scripts/ifcfg-_`suffix`_`` files. If it finds an `ifcfg` file with a **HWADDR** entry matching the MAC address of an interface it renames the interface to the name given in the `ifcfg` file by the **DEVICE** directive.

1. A rule in `/usr/lib/udev/rules.d/71-biosdevname.rules` instructs biosdevname to rename the interface according to its naming policy, provided that it was not renamed in a previous step, biosdevname is installed, and **biosdevname=0** was not given as a kernel command on the boot command line.

1. A rule in `/lib/udev/rules.d/75-net-description.rules` instructs udev to fill in the internal udev device property values ID\_NET\_NAME\_ONBOARD, ID\_NET\_NAME\_SLOT, ID\_NET\_NAME\_PATH, ID\_NET\_NAME\_MAC by examining the network interface device. Note, that some device properties might be undefined.

1. A rule in `/usr/lib/udev/rules.d/80-net-name-slot.rules` instructs udev to rename the interface, provided that it was not renamed in step 1 or 2, and the kernel parameter **net.ifnames=0** was not given, according to the following priority: ID\_NET\_NAME\_ONBOARD, ID\_NET\_NAME\_SLOT, ID\_NET\_NAME\_PATH. It falls through to the next in the list, if one is unset. If none of these are set, then the interface will not be renamed.

Steps 3 and 4 are implementing the naming schemes 1, 2, 3, and optionally 4, described in [Section 8.1, “Naming Schemes Hierarchy”](#sec-Naming_Schemes_Hierarchy "8.1. Naming Schemes Hierarchy"). Step 2 is explained in more detail in [Section 8.6, “Consistent Network Device Naming Using biosdevname”](#sec-Consistent_Network_Device_Naming_Using_biosdevname "8.6. Consistent Network Device Naming Using biosdevname").

## 8\.3. Understanding the Predictable Network Interface Device Names	{#sec-Understanding_the_Predictable_Network_Interface_Device_Names}

The names have two character prefixes based on the type of interface:

1. `en` for Ethernet,

1. `wl` for wireless LAN (WLAN),

1. `ww` for wireless wide area network (WWAN).

The names have the following types:

Table 8.1. Device Name Types

|Format|Description|
|-|
|o&lt;_`index`_&gt;|on-board device index number|
|s&lt;_`slot>`_[f&lt;_`function>`_]\[d&lt;_`dev_id`_&gt;]|hotplug slot index number|
|x&lt;_`MAC`_&gt;|MAC address|
|p&lt;_`bus`_&gt;s&lt;_`slot`_&gt;[f&lt;_`function`_&gt;]\[d&lt;_`dev_id`_&gt;]|PCI geographical location|
|p&lt;_`bus`_&gt;s&lt;_`slot`_&gt;[f&lt;_`function`_&gt;]\[u&lt;_`port`_&gt;]\[..]\[c&lt;_`config`_&gt;]\[i&lt;_`interface`_&gt;]|USB port number chain|

<br />

* All multi-function PCI devices will carry the [f&lt;_`function`_&gt;] number in the device name, including the function 0 device.

* For USB devices the full chain of port numbers of hubs is composed. If the name gets longer than the maximum number of 15 characters, the name is not exported.

* The USB configuration descriptors == 1 and USB interface descriptors == 0 values are suppressed (configuration == 1 and interface == 0 are the default values if only one USB configuration or interface exists).

## 8\.4. Naming Scheme for Network Devices Available for Linux on System z	{#sec-Naming_Scheme_for_Network_Devices_Available_for_Linux_on_System_z}

Use the bus-ID to create predictable device names for network interfaces in Linux on System z instances. The bus-ID identifies a device in the s390 channel subsystem. A bus ID identifies the device within the scope of a Linux instance. For a CCW device, the bus ID is the device's device number with a leading `0.n`, where `n` is the subchannel set ID. For example, `0.1.0ab1`.

Network interfaces of device type Ethernet are named as follows:

	enccw_`0`_._`0`_._`1234`_

CTC network devices of device type SLIP are named as follows:

	slccw_`0`_._`0`_._`1234`_

Use the **znetconf -c** command or the **lscss -a** command to display available network devices and their bus-IDs.

Table 8.2. Device Name Types for Linux on System z

|Format|Description|
|-|
|enccw_`bus-ID`_|device type Ethernet|
|slccw_`bus-ID`_|CTC network devices of device type SLIP|

<br />

## 8\.5. Naming Scheme for VLAN Interfaces	{#sec-Naming_Scheme_for_VLAN_Interfaces}

Traditionally, VLAN interface names in the format: _`interface-name`_._`VLAN-ID`_ are used. The `VLAN-ID` ranges from `0` to `4096`, which is a maximum of four characters and the total interface name has a limit of 15 characters. The maximum interface name length is defined by the kernel headers and is a global limit, affecting all applications.

In Fedora, four naming conventions for VLAN interface names are supported:

VLAN plus VLAN ID
:    The word `vlan` plus the VLAN ID. For example: vlan0005

VLAN plus VLAN ID without padding
:    The word `vlan` plus the VLAN ID with out padding by means of an additional two zeros. For example: vlan5

Device name plus VLAN ID
:    The name of the parent interface plus the VLAN ID. For example: eth0.0005

Device name plus VLAN ID without padding
:    The name of the parent interface plus the VLAN ID with out padding by means of an additional two zeros. For example: eth0.05

## 8\.6. Consistent Network Device Naming Using biosdevname	{#sec-Consistent_Network_Device_Naming_Using_biosdevname}

This feature, implemented via the biosdevname udev helper utility, will change the name of all embedded network interfaces, PCI card network interfaces, and virtual function network interfaces from the existing `eth[0123…]` to the new naming convention as shown in [Table 8.3, “The biosdevname Naming Convention”](#tabl-Consistent_Network_Device_Naming_biosdevname "Table 8.3. The biosdevname Naming Convention"). Note that unless the system is a Dell system, or biosdevname is explicitly enabled as described in [Section 8.6.2, “Enabling and Disabling the Feature”](#sec-Consistent_Network_Device_Naming-Enabling_and_Disabling "8.6.2. Enabling and Disabling the Feature"), the `systemd` naming scheme will take precedence.

Table 8.3. The biosdevname Naming Convention

|Device|Old Name|New Name|
|-|
|Embedded network interface (LOM)|`eth[0123…]`|`em[1234…]`[[a]](#ftn.idm16356864)|
|PCI card network interface|`eth[0123…]`|``p<_`slot`_>p<_`ethernet port`_>``[[b]](#ftn.idp13962960)|
|Virtual function|`eth[0123…]`|``p<_`slot`_>p<_`ethernet port`_>_<_`virtual interface`_>``[[c]](#ftn.idm27566912)|
|[[a] ](#idm16356864) New enumeration starts at `1`.

[[b] ](#idp13962960) For example: `p3p4`

[[c] ](#idm27566912) For example: `p3p4_1`|

<br />

### 8\.6.1. System Requirements	{#sec-Consistent_Network_Device_Naming-System_Requirements}

The biosdevname program uses information from the system's BIOS, specifically the _type 9_ (System Slot) and _type 41_ (Onboard Devices Extended Information) fields contained within the SMBIOS. If the system's BIOS does not have SMBIOS version 2.6 or higher and this data, the new naming convention will not be used. Most older hardware does not support this feature because of a lack of BIOSes with the correct SMBIOS version and field information. For BIOS or SMBIOS version information, contact your hardware vendor.

For this feature to take effect, the biosdevname package must also be installed. To install it, issue the following command as `root`:

	~]# **yum install biosdevname**

### 8\.6.2. Enabling and Disabling the Feature	{#sec-Consistent_Network_Device_Naming-Enabling_and_Disabling}

To disable this feature, pass the following option on the boot command line, both during and after installation:

    biosdevname=0

To enable this feature, pass the following option on the boot command line, both during and after installation:

    biosdevname=1

Unless the system meets the minimum requirements, this option will be ignored and the system will use the `systemd` naming scheme as described in the beginning of the chapter.

If the `biosdevname` install option is specified, it must remain as a boot option for the lifetime of the system.

## 8\.7. Notes for Administrators	{#sec-Consistent_Network_Device_Naming-Notes}

Many system customization files can include network interface names, and thus will require updates if moving a system from the old convention to the new convention. If you use the new naming convention, you will also need to update network interface names in areas such as custom iptables rules, scripts altering `irqbalance`, and other similar configuration files. Also, enabling this change for installation will require modification to existing kickstart files that use device names via the `ksdevice` parameter; these kickstart files will need to be updated to use the network device's MAC address or the network device's new name.

### Note

The maximum interface name length is defined by the kernel headers and is a global limit, affecting all applications.

## 8\.8. Controlling the Selection of Network Device Names	{#sec-Controlling_the_Selection_of_Network_Device_Names}

Device naming can be controlled in the following manner:

By identifying the network interface device
:    Setting the MAC address in an `ifcfg` file using the **HWADDR** directive enables it to be identified by udev. The name will be taken from the string given by the **DEVICE** directive, which by convention is the same as the `ifcfg` suffix. For example, `ifcfg`-_`eth0`_.

By turning on or off biosdevname
:    The name provided by biosdevname will be used (if biosdevname can determine one).

By turning on or off the `systemd-udev` naming scheme
:    The name provided by `systemd-udev` will be used (if `systemd-udev` can determine one).

## 8\.9. Disabling Consistent Network Device Naming	{#sec-Disabling_Consistent_Network_Device_Naming}

To disable consistent network device naming, choose from one of the following:

* Disable the assignment of fixed names, so that the unpredictable kernel names are used again, by masking udev's rule file for the default policy. This “masking” can be done by making a symbolic link to `/dev/null`. As `root`, issue a command as follows:

	~]# **ln -s /dev/null /etc/udev/rules.d/80-net-name-slot.rules**

* Create your own manual naming scheme, for example by naming your interfaces “internet0”, “dmz0” or “lan0”. To do that create your own udev rules file and set the NAME property for the devices. Make sure to order it before the default policy file, for example by naming it `/etc/udev/rules.d/70-my-net-names.rules`.

* Alter the default policy file to pick a different naming scheme, for example to name all interfaces after their MAC address by default. As `root` copy the default policy file as follows:

	~]# **cp /usr/lib/udev/rules.d/80-net-name-slot.rules /etc/udev/rules.d/80-net-name-slot.rules**

    Edit the file in the `/etc/udev/rules.d/` directory and change the lines as necessary.

* Add the following line to the `/etc/default/grub` file:

	net.ifnames=0

    or pass it to the kernel at boot time using the GRUB2 command line interface. For more information about GRUB2 see [_Fedora 20 System Administrator's Guide_](https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/System_Administrators_Guide/).

## 8\.10. Troubleshooting Network Device Naming	{#sec_Troubleshooting_Network_Device_Naming}

Predictable interface names will be assigned for each interface, if applicable, as per the procedure described in [Section 8.2, “Understanding the Device Renaming Procedure”](#sec-Understanding_the_Device_Renaming_Procedure "8.2. Understanding the Device Renaming Procedure"). To view the list of possible names udev will use, issue a command in the following form as `root`:

	~]# **udevadm info /sys/class/net/_`ifname`_ | grep ID_NET_NAME**

where _`ifname`_ is one of the interfaces listed by the following command:

	~]$ **ls /sys/class/net/**

One of the possible names will be applied by udev according to the rules as described in [Section 8.2, “Understanding the Device Renaming Procedure”](#sec-Understanding_the_Device_Renaming_Procedure "8.2. Understanding the Device Renaming Procedure"), and summarized here:

* `/usr/lib/udev/rules.d/60-net.rules` - from initscripts,

* `/usr/lib/udev/rules.d/71-biosdevname.rules` - from biosdevname,

* `/usr/lib/udev/rules.d/80-net-name-slot.rules` - from `systemd`

From the above list of rule files it can be seen that if interface naming is done via initscripts or biosdevname it always takes precedence over udev native naming. However if initscripts renaming is not taking place and biosdevname is disabled, then to alter the interface names copy the `80-net-name-slot.rules` from `/usr/` to `/etc/` and edit the file appropriately. In other words, comment out or arrange schemes to be used in a certain order.

Example 8.1. Some interfaces have names from the kernel namespace (eth[0,1,2...]) while others are successfully renamed by udev

Mixed up schemes most likely means that either for some hardware there is no usable information provided by the kernel to udev, thus it could not figure out any names, or the information provided to udev is not suitable, for example non-unique device IDs. The latter is more common and the solution is to use a custom naming scheme in ifcfg files or alter which udev scheme is in use by editing 80-net-name-slot.rules.

<br />

Example 8.2. In /var/log/messages or the systemd journal, renaming is seen to be done twice for each interface

Systems with the naming scheme encoded in ifcfg files but which do not have a regenerated `initrd` image are likely to encounter this issue. The interface name is initially assigned (via biosdevname or udev or dracut parameters on the kernel command line) during early-boot while still in `initrd`. Then after switching to real `rootfs`, renaming is done a second time and a new interface name is determined by the `/usr/lib/udev/rename_device` binary spawned by udev because of processing 60-net.rules. You can safely ignore such messages.

<br />

Example 8.3. Using naming scheme in ifcfg files with ethX names does not work

Use of interface names from kernel namespace is discouraged. To get predictable and stable interface names please use some other prefix than "eth".

<br />

## 8\.11. Additional Resources	{#sec-Consistent_Network_Device_Naming-additional_resources}

The following sources of information provide additional resources regarding Network Teaming.

### 8\.11.1. Installed Documentation	{#sec-Consistent_Network_Device_Naming-docs-inst}

* `udev(7)` man page — Describes the Linux dynamic device management daemon, `udevd`.

* `systemd(1)` man page — Describes `systemd` system and service manager.

* `biosdevname(1)` man page — Describes the utility for obtaining the BIOS-given name of a device.

# Part II. Servers	{#part-Servers}

This part discusses how to set up servers normally required for networking.

## Chapter 9. DHCP Servers	{#ch-DHCP_Servers}

Dynamic Host Configuration Protocol (DHCP) is a network protocol that automatically assigns TCP/IP information to client machines. Each `DHCP` client connects to the centrally located `DHCP` server, which returns the network configuration (including the `IP` address, gateway, and `DNS` servers) of that client.

## 9\.1. Why Use DHCP?	{#sec-dhcp-why}

`DHCP` is useful for automatic configuration of client network interfaces. When configuring the client system, you can choose `DHCP` instead of specifying an `IP` address, netmask, gateway, or `DNS` servers. The client retrieves this information from the `DHCP` server. `DHCP` is also useful if you want to change the `IP` addresses of a large number of systems. Instead of reconfiguring all the systems, you can just edit one configuration file on the server for the new set of `IP` addresses. If the `DNS` servers for an organization changes, the changes happen on the `DHCP` server, not on the `DHCP` clients. When you restart the network or reboot the clients, the changes go into effect.

If an organization has a functional `DHCP` server correctly connected to a network, laptops and other mobile computer users can move these devices from office to office.

Note that administrators of `DNS` and `DHCP` servers, as well as any provisioning applications, should agree on the host name format used in an organization. See [Section 3.1.1, “Recommended Naming Practices”](#sec-Recommended_Naming_Practices "3.1.1. Recommended Naming Practices") for more information on the format of host names.

## 9\.2. Configuring a DHCP Server	{#sec-dhcp-configuring-server}

The dhcp package contains an _Internet Systems Consortium_ (ISC) `DHCP` server. Install the package as `root`:

	~]# **yum install dhcp**

Installing the dhcp package creates a file, `/etc/dhcp/dhcpd.conf`, which is merely an empty configuration file. As `root`, issue the following command:

	~]# **cat /etc/dhcp/dhcpd.conf**
	#
	# DHCP Server Configuration file.
	#   see /usr/share/doc/dhcp/dhcpd.conf.example
	#   see dhcpd.conf(5) man page
	#

The example configuration file can be found at `/usr/share/doc/dhcp/dhcpd.conf.example`. You should use this file to help you configure `/etc/dhcp/dhcpd.conf`, which is explained in detail below.

`DHCP` also uses the file `/var/lib/dhcpd/dhcpd.leases` to store the client lease database. Refer to [Section 9.2.2, “Lease Database”](#lease-database "9.2.2. Lease Database") for more information.

### 9\.2.1. Configuration File	{#config-file}

The first step in configuring a `DHCP` server is to create the configuration file that stores the network information for the clients. Use this file to declare options for client systems.

The configuration file can contain extra tabs or blank lines for easier formatting. Keywords are case-insensitive and lines beginning with a hash sign (`#`) are considered comments.

There are two types of statements in the configuration file:

* Parameters — State how to perform a task, whether to perform a task, or what network configuration options to send to the client.

* Declarations — Describe the topology of the network, describe the clients, provide addresses for the clients, or apply a group of parameters to a group of declarations.

The parameters that start with the keyword option are referred to as _options_. These options control `DHCP` options; whereas, parameters configure values that are not optional or control how the `DHCP` server behaves.

Parameters (including options) declared before a section enclosed in curly brackets (`{ }`) are considered global parameters. Global parameters apply to all the sections below it.

### Restart the DHCP Daemon for the Changes to Take Effect

If the configuration file is changed, the changes do not take effect until the `DHCP` daemon is restarted with the command **systemctl restart dhcpd**.

### Use the omshell Command

Instead of changing a `DHCP` configuration file and restarting the service each time, using the **omshell** command provides an interactive way to connect to, query, and change the configuration of a `DHCP` server. By using **omshell**, all changes can be made while the server is running. For more information on **omshell**, see the **omshell** man page.

In [Example 9.1, “Subnet Declaration”](#subnet "Example 9.1. Subnet Declaration"), the **routers**, **subnet-mask**, **domain-search**, **domain-name-servers**, and **time-offset** options are used for any **host** statements declared below it.

For every subnet which will be served, and for every subnet to which the `DHCP` server is connected, there must be one **subnet** declaration, which tells the `DHCP` daemon how to recognize that an address is on that subnet. A **subnet** declaration is required for each subnet even if no addresses will be dynamically allocated to that subnet.

In this example, there are global options for every `DHCP` client in the subnet and a **range** declared. Clients are assigned an `IP` address within the **range**.

Example 9.1. Subnet Declaration

	subnet 192.168.1.0 netmask 255.255.255.0 {
	        option routers                  192.168.1.254;
	        option subnet-mask              255.255.255.0;
	        option domain-search              "example.com";
	        option domain-name-servers       192.168.1.1;
	        option time-offset              -18000;     # Eastern Standard Time
		range 192.168.1.10 192.168.1.100;
	}

<br />

To configure a `DHCP` server that leases a dynamic `IP` address to a system within a subnet, modify the example values from [Example 9.2, “Range Parameter”](#dynamic-ip "Example 9.2. Range Parameter"). It declares a default lease time, maximum lease time, and network configuration values for the clients. This example assigns `IP` addresses in the **range** `192.168.1.10` and `192.168.1.100` to client systems.

Example 9.2. Range Parameter

	default-lease-time 600;
	max-lease-time 7200;
	option subnet-mask 255.255.255.0;
	option broadcast-address 192.168.1.255;
	option routers 192.168.1.254;
	option domain-name-servers 192.168.1.1, 192.168.1.2;
	option domain-search "example.com";
	subnet 192.168.1.0 netmask 255.255.255.0 {
	   range 192.168.1.10 192.168.1.100;
	}

<br />

To assign an `IP` address to a client based on the MAC address of the network interface card, use the **hardware ethernet** parameter within a **host** declaration. As demonstrated in [Example 9.3, “Static IP Address Using DHCP”](#static-ip "Example 9.3. Static IP Address Using DHCP"), the **host apex** declaration specifies that the network interface card with the MAC address `00:A0:78:8E:9E:AA` always receives the `IP` address `192.168.1.4`.

Note that you can also use the optional parameter `host-name` to assign a host name to the client.

Example 9.3. Static IP Address Using DHCP

	host apex {
	   option host-name "apex.example.com";
	   hardware ethernet 00:A0:78:8E:9E:AA;
	   fixed-address 192.168.1.4;
	}

<br />

All subnets that share the same physical network should be declared within a **shared-network** declaration as shown in [Example 9.4, “Shared-network Declaration”](#shared-network "Example 9.4. Shared-network Declaration"). Parameters within the **shared-network**, but outside the enclosed subnet declarations, are considered to be global parameters. The name assigned to **shared-network** must be a descriptive title for the network, such as using the title “test-lab” to describe all the subnets in a test lab environment.

Example 9.4. Shared-network Declaration

	shared-network name {
	    option domain-search              "test.redhat.com";
	    option domain-name-servers      ns1.redhat.com, ns2.redhat.com;
	    option routers                  192.168.0.254;
	    #more parameters for EXAMPLE shared-network
	    subnet 192.168.1.0 netmask 255.255.252.0 {
	        #parameters for subnet
	        range 192.168.1.1 192.168.1.254;
	    }
	    subnet 192.168.2.0 netmask 255.255.252.0 {
	        #parameters for subnet
	        range 192.168.2.1 192.168.2.254;
	    }
	}

<br />

As demonstrated in [Example 9.5, “Group Declaration”](#group "Example 9.5. Group Declaration"), the **group** declaration is used to apply global parameters to a group of declarations. For example, shared networks, subnets, and hosts can be grouped.

Example 9.5. Group Declaration

	group {
	   option routers                  192.168.1.254;
	   option subnet-mask              255.255.255.0;
	   option domain-search              "example.com";
	   option domain-name-servers       192.168.1.1;
	   option time-offset              -18000;     # Eastern Standard Time
	   host apex {
	      option host-name "apex.example.com";
	      hardware ethernet 00:A0:78:8E:9E:AA;
	      fixed-address 192.168.1.4;
	   }
	   host raleigh {
	      option host-name "raleigh.example.com";
	      hardware ethernet 00:A1:DD:74:C3:F2;
	      fixed-address 192.168.1.6;
	   }
	}

<br />

### Using the Example Configuration File

You can use the provided example configuration file as a starting point and add custom configuration options to it. To copy this file to the proper location, use the following command as `root`:

	~]# **cp /usr/share/doc/dhcp-_`version_number`_/dhcpd.conf.example /etc/dhcp/dhcpd.conf**

... where _`version_number`_ is the `DHCP` version number.

For a complete list of option statements and what they do, see the `dhcp-options(5)` man page.

### 9\.2.2. Lease Database	{#lease-database}

On the `DHCP` server, the file `/var/lib/dhcpd/dhcpd.leases` stores the `DHCP` client lease database. Do not change this file. `DHCP` lease information for each recently assigned `IP` address is automatically stored in the lease database. The information includes the length of the lease, to whom the `IP` address has been assigned, the start and end dates for the lease, and the MAC address of the network interface card that was used to retrieve the lease.

All times in the lease database are in Coordinated Universal Time (UTC), not local time.

The lease database is recreated from time to time so that it is not too large. First, all known leases are saved in a temporary lease database. The `dhcpd.leases` file is renamed `dhcpd.leases~` and the temporary lease database is written to `dhcpd.leases`.

The `DHCP` daemon could be killed or the system could crash after the lease database has been renamed to the backup file but before the new file has been written. If this happens, the `dhcpd.leases` file does not exist, but it is required to start the service. Do not create a new lease file. If you do, all old leases are lost which causes many problems. The correct solution is to rename the `dhcpd.leases~` backup file to `dhcpd.leases` and then start the daemon.

### 9\.2.3. Starting and Stopping the Server	{#idp4000176}

### Starting the DHCP Server for the First Time

When the `DHCP` server is started for the first time, it fails unless the `dhcpd.leases` file exists. You can use the command **touch /var/lib/dhcpd/dhcpd.leases** to create the file if it does not exist. If the same server is also running BIND as a `DNS` server, this step is not necessary, as starting the **named** service automatically checks for a `dhcpd.leases` file.

Do not create a new lease file on a system that was previously running. If you do, all old leases are lost which causes many problems. The correct solution is to rename the `dhcpd.leases~` backup file to `dhcpd.leases` and then start the daemon.

To start the `DHCP` service, use the following command:

	**systemctl start dhcpd.service**

To stop the `DHCP` server, type:

	**systemctl stop dhcpd.service**

By default, the `DHCP` service does not start at boot time. To configure the daemon to start automatically at boot time, run:

	**systemctl enable dhcpd.service**

If more than one network interface is attached to the system, but the `DHCP` server should only listen for `DHCP` requests on one of the interfaces, configure the `DHCP` server to listen only on that device. The `DHCP` daemon will only listen on interfaces for which it finds a subnet declaration in the `/etc/dhcp/dhcpd.conf` file.

This is useful for a firewall machine with two network cards. One network card can be configured as a `DHCP` client to retrieve an `IP` address to the Internet. The other network card can be used as a `DHCP` server for the internal network behind the firewall. Specifying only the network card connected to the internal network makes the system more secure because users can not connect to the daemon via the Internet.

To specify command-line options, copy and then edit the `dhcpd.service` file as the `root` user. For example, as follows:

	~]# **cp /usr/lib/systemd/system/dhcpd.service /etc/systemd/system/**
	~]# **vi /etc/systemd/system/dhcpd.service**

Edit the line under section [Service]:

	ExecStart=/usr/sbin/dhcpd -f -cf /etc/dhcp/dhcpd.conf -user dhcpd -group dhcpd --no-pid _`your_interface_name(s)`_

Then, as the `root` user, restart the service:

	~]# **systemctl --system daemon-reload**
	~]# **systemctl restart dhcpd**

Command line options can be appended to **ExecStart=/usr/sbin/dhcpd** in the `/etc/systemd/system/dhcpd.service` unit file under section [Service]. They include:

* **-p _`portnum`_** — Specifies the UDP port number on which **dhcpd** should listen. The default is port 67. The `DHCP` server transmits responses to the `DHCP` clients at a port number one greater than the UDP port specified. For example, if the default port 67 is used, the server listens on port 67 for requests and responds to the client on port 68. If a port is specified here and the `DHCP` relay agent is used, the same port on which the `DHCP` relay agent should listen must be specified. See [Section 9.3, “DHCP Relay Agent”](#dhcp-relay-agent "9.3. DHCP Relay Agent") for details.

* **-f** — Runs the daemon as a foreground process. This is mostly used for debugging.

* **-d** — Logs the `DHCP` server daemon to the standard error descriptor. This is mostly used for debugging. If this is not specified, the log is written to `/var/log/messages`.

* **-cf _`filename`_ ** — Specifies the location of the configuration file. The default location is `/etc/dhcp/dhcpd.conf`.

* **-lf _`filename`_ ** — Specifies the location of the lease database file. If a lease database file already exists, it is very important that the same file be used every time the `DHCP` server is started. It is strongly recommended that this option only be used for debugging purposes on non-production machines. The default location is `/var/lib/dhcpd/dhcpd.leases`.

* **-q** — Do not print the entire copyright message when starting the daemon.

## 9\.3. DHCP Relay Agent	{#dhcp-relay-agent}

The DHCP Relay Agent (dhcrelay) enables the relay of `DHCP` and `BOOTP` requests from a subnet with no `DHCP` server on it to one or more `DHCP` servers on other subnets.

When a `DHCP` client requests information, the DHCP Relay Agent forwards the request to the list of `DHCP` servers specified when the DHCP Relay Agent is started. When a `DHCP` server returns a reply, the reply is broadcast or unicast on the network that sent the original request.

The DHCP Relay Agent for `IPv4`, dhcrelay, listens for `DHCPv4` and `BOOTP` requests on all interfaces unless the interfaces are specified in `/etc/sysconfig/dhcrelay` with the `INTERFACES` directive. See [Section 9.3.2, “Configure dhcrelay as a DHCPv6 relay agent”](#sec-Configure_dhcrelay_as_a_DHCPv6_relay_agent "9.3.2. Configure dhcrelay as a DHCPv6 relay agent"). The DHCP Relay Agent for `IPv6`, dhcrelay6, does not have this default behavior and interfaces to listen for `DHCPv6` requests must be specified. See [Section 9.3.2, “Configure dhcrelay as a DHCPv6 relay agent”](#sec-Configure_dhcrelay_as_a_DHCPv6_relay_agent "9.3.2. Configure dhcrelay as a DHCPv6 relay agent").

dhcrelay can either be run as a `DHCPv4` and `BOOTP` relay agent (by default) or as a `DHCPv6` relay agent (with `-6` argument). To see the usage message, issue the command **dhcrelay -h**.

### 9\.3.1. Configure dhcrelay as a DHCPv4 and BOOTP relay agent	{#sec-Configure_dhcrelay_as_a_DHCPv4_and_BOOTP_relay_agent}

To run dhcrelay in `DHCPv4` and `BOOTP` mode specify the servers to which the requests should be forwarded to. Copy and then edit the `dhcrelay.service` file as the `root` user:

	~]# **cp /lib/systemd/system/dhcrelay.service /etc/systemd/system/**
	~]# **vi /etc/systemd/system/dhcrelay.service**

Edit the `ExecStart` option under section [Service] and add one or more server `IPv4` addresses to the end of the line, for example:

	ExecStart=/usr/sbin/dhcrelay -d --no-pid 192.168.1.1

If you also want to specify interfaces where the DHCP Relay Agent listens for `DHCP` requests, add them to the `ExecStart` option with `-i` argument (otherwise it will listen on all interfaces), for example:

	ExecStart=/usr/sbin/dhcrelay -d --no-pid 192.168.1.1 -i em1

For other options see the `dhcrelay(8)` man page.

To activate the changes made, as the `root` user, restart the service:

	~]# **systemctl --system daemon-reload**
	~]# **systemctl restart dhcrelay**

### 9\.3.2. Configure dhcrelay as a DHCPv6 relay agent	{#sec-Configure_dhcrelay_as_a_DHCPv6_relay_agent}

To run dhcrelay in `DHCPv6` mode add the `-6` argument and specify the “lower interface” (on which queries will be received from clients or from other relay agents) and the “upper interface” (to which queries from clients and other relay agents should be forwarded). Copy `dhcrelay.service` to `dhcrelay6.service` and edit it as the `root` user:

	~]# **cp /lib/systemd/system/dhcrelay.service /etc/systemd/system/dhcrelay6.service**
	~]# **vi /etc/systemd/system/dhcrelay6.service**

Edit the `ExecStart` option under section [Service] add `-6` argument and add the “lower interface” and “upper interface” interface, for example:

	ExecStart=/usr/sbin/dhcrelay -d --no-pid -6 -l em1 -u em2

For other options see the `dhcrelay(8)` man page.

To activate the changes made, as the `root` user, restart the service:

	~]# **systemctl --system daemon-reload**
	~]# **systemctl restart dhcrelay6**

## 9\.4. Configuring a Multihomed DHCP Server	{#sec-Configuring_a_Multihomed_DHCP_Server}

A multihomed `DHCP` server serves multiple networks, that is, multiple subnets. The examples in these sections detail how to configure a `DHCP` server to serve multiple networks, select which network interfaces to listen on, and how to define network settings for systems that move networks.

Before making any changes, back up the existing `/etc/dhcp/dhcpd.conf` file.

The `DHCP` daemon will only listen on interfaces for which it finds a subnet declaration in the `/etc/dhcp/dhcpd.conf` file.

The following is a basic `/etc/dhcp/dhcpd.conf` file, for a server that has two network interfaces, eth0 in a `10.0.0.0/24` network, and eth1 in a `172.16.0.0/24` network. Multiple `subnet` declarations allow you to define different settings for multiple networks:

	default-lease-time _`600`_;
	max-lease-time _`7200`_;
	subnet 10.0.0.0 netmask 255.255.255.0 {
		option subnet-mask 255.255.255.0;
		option routers 10.0.0.1;
		range 10.0.0.5 10.0.0.15;
	}
	subnet 172.16.0.0 netmask 255.255.255.0 {
		option subnet-mask 255.255.255.0;
		option routers 172.16.0.1;
		range 172.16.0.5 172.16.0.15;
	}

``subnet _`10.0.0.0`_ netmask _`255.255.255.0`_;``
:    A `subnet` declaration is required for every network your `DHCP` server is serving. Multiple subnets require multiple `subnet` declarations. If the `DHCP` server does not have a network interface in a range of a `subnet` declaration, the `DHCP` server does not serve that network.

If there is only one `subnet` declaration, and no network interfaces are in the range of that subnet, the `DHCP` daemon fails to start, and an error such as the following is logged to `/var/log/messages`:

	dhcpd: No subnet declaration for eth0 (0.0.0.0).
	dhcpd: ** Ignoring requests on eth0.  If this is not what
	dhcpd:    you want, please write a subnet declaration
	dhcpd:    in your dhcpd.conf file for the network segment
	dhcpd:    to which interface eth1 is attached. **
	dhcpd:
	dhcpd:
	dhcpd: Not configured to listen on any interfaces!

``option subnet-mask _`255.255.255.0`_;``
:    The `option subnet-mask` option defines a subnet mask, and overrides the `netmask` value in the `subnet` declaration. In simple cases, the subnet and netmask values are the same.

``option routers _`10.0.0.1`_;``
:    The `option routers` option defines the default gateway for the subnet. This is required for systems to reach internal networks on a different subnet, as well as external networks.

``range _`10.0.0.5`_ _`10.0.0.15`_;``
:    The `range` option specifies the pool of available `IP` addresses. Systems are assigned an address from the range of specified `IP` addresses.

For further information, see the `dhcpd.conf(5)` man page.

### 9\.4.1. Host Configuration	{#sec-dns_Host_Configuration}

Before making any changes, back up the existing `/etc/sysconfig/dhcpd` and `/etc/dhcp/dhcpd.conf` files.

Configuring a Single System for Multiple Networks.  The following `/etc/dhcp/dhcpd.conf` example creates two subnets, and configures an `IP` address for the same system, depending on which network it connects to:

	default-lease-time _`600`_;
	max-lease-time _`7200`_;
	subnet 10.0.0.0 netmask 255.255.255.0 {
		option subnet-mask 255.255.255.0;
		option routers 10.0.0.1;
		range 10.0.0.5 10.0.0.15;
	}
	subnet 172.16.0.0 netmask 255.255.255.0 {
		option subnet-mask 255.255.255.0;
		option routers 172.16.0.1;
		range 172.16.0.5 172.16.0.15;
	}
	host example0 {
		hardware ethernet 00:1A:6B:6A:2E:0B;
		fixed-address 10.0.0.20;
	}
	host example1 {
		hardware ethernet 00:1A:6B:6A:2E:0B;
		fixed-address 172.16.0.20;
	}

``host _`example0`_ ``
:    The `host` declaration defines specific parameters for a single system, such as an `IP` address. To configure specific parameters for multiple hosts, use multiple `host` declarations.

Most `DHCP` clients ignore the name in `host` declarations, and as such, this name can be anything, as long as it is unique to other `host` declarations. To configure the same system for multiple networks, use a different name for each `host` declaration, otherwise the `DHCP` daemon fails to start. Systems are identified by the `hardware ethernet` option, not the name in the `host` declaration.

``hardware ethernet _`00:1A:6B:6A:2E:0B`_;``
:    The `hardware ethernet` option identifies the system. To find this address, run the **ip link** command.

``fixed-address _`10.0.0.20`_;``
:    The `fixed-address` option assigns a valid `IP` address to the system specified by the `hardware ethernet` option. This address must be outside the `IP` address pool specified with the `range` option.

If `option` statements do not end with a semicolon, the `DHCP` daemon fails to start, and an error such as the following is logged to `/var/log/messages`:

	/etc/dhcp/dhcpd.conf line 20: semicolon expected.
	dhcpd: }
	dhcpd: ^
	dhcpd: /etc/dhcp/dhcpd.conf line 38: unexpected end of file
	dhcpd:
	dhcpd: ^
	dhcpd: Configuration file errors encountered -- exiting

Configuring Systems with Multiple Network Interfaces.  The following `host` declarations configure a single system, which has multiple network interfaces, so that each interface receives the same `IP` address. This configuration will not work if both network interfaces are connected to the same network at the same time:

	host interface0 {
		hardware ethernet 00:1a:6b:6a:2e:0b;
		fixed-address 10.0.0.18;
	}
	host interface1 {
		hardware ethernet 00:1A:6B:6A:27:3A;
		fixed-address 10.0.0.18;
	}

For this example, `interface0` is the first network interface, and `interface1` is the second interface. The different `hardware ethernet` options identify each interface.

If such a system connects to another network, add more `host` declarations, remembering to:

* assign a valid `fixed-address` for the network the host is connecting to.

* make the name in the `host` declaration unique.

When a name given in a `host` declaration is not unique, the `DHCP` daemon fails to start, and an error such as the following is logged to `/var/log/messages`:

	dhcpd: /etc/dhcp/dhcpd.conf line 31: host interface0: already exists
	dhcpd: }
	dhcpd: ^
	dhcpd: Configuration file errors encountered -- exiting

This error was caused by having multiple `host interface0` declarations defined in `/etc/dhcp/dhcpd.conf`.

## 9\.5. DHCP for IPv6 (DHCPv6)	{#sec-dhcp_for_ipv6_dhcpv6}

The ISC `DHCP` includes support for `IPv6` (`DHCPv6`) since the 4.x release with a `DHCPv6` server, client, and relay agent functionality. The agents support both `IPv4` and `IPv6`, however the agents can only manage one protocol at a time; for dual support they must be started separately for `IPv4` and `IPv6`. For example, configure both `DHCPv4` and `DHCPv6` by editing their respective configuration files `/etc/dhcp/dhcpd.conf` and `/etc/dhcp/dhcpd6.conf` and then issue the following commands:

	~]# **systemctl start dhcpd**
	~]# **systemctl start dhcpd6**

The `DHCPv6` server configuration file can be found at `/etc/dhcp/dhcpd6.conf`.

The example server configuration file can be found at `/usr/share/doc/dhcp/dhcpd6.conf.example`.

A simple `DHCPv6` server configuration file can look like this:

	subnet6 2001:db8:0:1::/64 {
	        range6 2001:db8:0:1::129 2001:db8:0:1::254;
	        option dhcp6.name-servers fec0:0:0:1::1;
	        option dhcp6.domain-search "domain.example";
	}

## 9\.6. Additional Resources	{#sec-dhcp-additional-resources}

For additional information, see _The DHCP Handbook; Ralph Droms and Ted Lemon; 2003_ or the following resources.

### 9\.6.1. Installed Documentation	{#sec-dhcp-installed-docs}

* `dhcpd(8)` man page — Describes how the `DHCP` daemon works.

* `dhcpd.conf(5)` man page — Explains how to configure the `DHCP` configuration file; includes some examples.

* `dhcpd.leases(5)` man page — Describes a persistent database of leases.

* `dhcp-options(5)` man page — Explains the syntax for declaring `DHCP` options in `dhcpd.conf`; includes some examples.

* `dhcrelay(8)` man page — Explains the `DHCP` Relay Agent and its configuration options.

* `/usr/share/doc/dhcp/` — Contains example configuration files.

* `/usr/share/doc/dhcp-common/` — Contains README files, and release notes for current versions of the `DHCP` service.

## Chapter 10. DNS Servers	{#ch-DNS_Servers}

`DNS` (Domain Name System), is a distributed database system that is used to associate host names with their respective `IP` addresses. For users, this has the advantage that they can refer to machines on the network by names that are usually easier to remember than the numerical network addresses. For system administrators, using a `DNS` server, also known as a _nameserver_, enables changing the `IP` address for a host without ever affecting the name-based queries. The use of the `DNS` databases is not only for resolving `IP` addresses to domain names and their use is becoming broader and broader as DNSSEC is deployed.

## 10\.1. Introduction to DNS	{#sec-Introduction_to_DNS}

`DNS` is usually implemented using one or more centralized servers that are authoritative for certain domains. When a client host requests information from a nameserver, it usually connects to port 53. The nameserver then attempts to resolve the name requested. If the nameserver is configured to be a recursive name servers and it does not have an authoritative answer, or does not already have the answer cached from an earlier query, it queries other nameservers, called _root nameservers_, to determine which nameservers are authoritative for the name in question, and then queries them to get the requested name. Nameservers configured as purely authoritative, with recursion disabled, will not do lookups on behalf of clients.

### 10\.1.1. Nameserver Zones	{#sec-dns-introduction-zones}

In a `DNS` server, all information is stored in basic data elements called _resource records_ (RR). Resource records are defined in [RFC 1034](http://www.rfc-editor.org/rfc/rfc1034.txt). The domain names are organized into a tree structure. Each level of the hierarchy is divided by a period (`.`). For example: The root domain, denoted by `.`, is the root of the `DNS` tree, which is at level zero. The domain name `com`, referred to as the _top-level domain_ (TLD) is a child of the root domain (`.`) so it is the first level of the hierarchy. The domain name `example.com` is at the second level of the hierarchy.

Example 10.1. A Simple Resource Record

An example of a simple _resource record_ (RR):

	example.com.      86400    IN         A           192.0.2.1

The domain name, `example.com`, is the _owner_ for the RR. The value `86400` is the _time to live_ (TTL). The letters `IN`, meaning “the Internet system”, indicate the _class_ of the RR. The letter `A` indicates the _type_ of RR (in this example, a host address). The host address `192.0.2.1` is the data contained in the final section of this RR. This one line example is a RR. A set of RRs with the same type, owner, and class is called a _resource record set_ (RRSet).

<br />

Zones are defined on authoritative nameservers through the use of _zone files_, which contain definitions of the resource records in each zone. Zone files are stored on _primary nameservers_ (also called _master nameservers_), where changes are made to the files, and _secondary nameservers_ (also called _slave nameservers_), which receive zone definitions from the primary nameservers. Both primary and secondary nameservers are authoritative for the zone and look the same to clients. Depending on the configuration, any nameserver can also serve as a primary or secondary server for multiple zones at the same time.

Note that administrators of `DNS` and `DHCP` servers, as well as any provisioning applications, should agree on the host name format used in an organization. See [Section 3.1.1, “Recommended Naming Practices”](#sec-Recommended_Naming_Practices "3.1.1. Recommended Naming Practices") for more information on the format of host names.

### 10\.1.2. Nameserver Types	{#sec-dns-introduction-nameservers}

There are two nameserver configuration types:

authoritative
:    Authoritative nameservers answer to resource records that are part of their zones only. This category includes both primary (master) and secondary (slave) nameservers.

recursive
:    Recursive nameservers offer resolution services, but they are not authoritative for any zone. Answers for all resolutions are cached in a memory for a fixed period of time, which is specified by the retrieved resource record.

Although a nameserver can be both authoritative and recursive at the same time, it is recommended not to combine the configuration types. To be able to perform their work, authoritative servers should be available to all clients all the time. On the other hand, since the recursive lookup takes far more time than authoritative responses, recursive servers should be available to a restricted number of clients only, otherwise they are prone to distributed denial of service (DDoS) attacks.

### 10\.1.3. BIND as a Nameserver	{#sec-dns-introduction-bind}

BIND consists of a set of DNS-related programs. It contains a nameserver called `named`, an administration utility called **rndc**, and a debugging tool called **dig**. See _Fedora 20 System Administrator's Guide_ for more information on how to run a service in Fedora.

## 10\.2. BIND	{#sec-BIND}

This section covers `BIND` (Berkeley Internet Name Domain), the `DNS` server included in Fedora. It focuses on the structure of its configuration files, and describes how to administer it both locally and remotely.

### 10\.2.1. Empty Zones	{#sec-bind-empty-zones}

`BIND` configures a number of “empty zones” to prevent recursive servers from sending unnecessary queries to Internet servers that cannot handle them (thus creating delays and SERVFAIL responses to clients who query for them). These empty zones ensure that immediate and authoritative NXDOMAIN responses are returned instead. The configuration option **empty-zones-enable** controls whether or not empty zones are created, whilst the option **disable-empty-zone** can be used in addition to disable one or more empty zones from the list of default prefixes that would be used.

The number of empty zones created for [_RFC 1918_](http://www.rfc-editor.org/info/rfc1918) prefixes has been increased, and users of `BIND 9.9` and above will see the [_RFC 1918_](http://www.rfc-editor.org/info/rfc1918) empty zones both when **empty-zones-enable** is unspecified (defaults to `yes`), and when it is explicitly set to `yes`.

### 10\.2.2. Configuring the named Service	{#sec-bind-namedconf}

When the `named` service is started, it reads the configuration from the files as described in [Table 10.1, “The named Service Configuration Files”](#table-bind-namedconf-files "Table 10.1. The named Service Configuration Files").

Table 10.1. The named Service Configuration Files

|Path|Description|
|-|
|`/etc/named.conf`|The main configuration file.|
|`/etc/named/`|An auxiliary directory for configuration files that are included in the main configuration file.|

<br />

The configuration file consists of a collection of statements with nested options surrounded by opening and closing curly brackets (`{` and `}`). Note that when editing the file, you have to be careful not to make any syntax error, otherwise the `named` service will not start. A typical `/etc/named.conf` file is organized as follows:

	_`statement-1`_ ["_`statement-1-name`_"] [_`statement-1-class`_] {
	  _`option-1`_;
	  _`option-2`_;
	  _`option-N`_;
	};
	_`statement-2`_ ["_`statement-2-name`_"] [_`statement-2-class`_] {
	  _`option-1`_;
	  _`option-2`_;
	  _`option-N`_;
	};
	_`statement-N`_ ["_`statement-N-name`_"] [_`statement-N-class`_] {
	  _`option-1`_;
	  _`option-2`_;
	  _`option-N`_;
	};

### Running BIND in a chroot environment

If you have installed the bind-chroot package, the BIND service will run in the **chroot** environment. In that case, the initialization script will mount the above configuration files using the **mount --bind** command, so that you can manage the configuration outside this environment. There is no need to copy anything into the `/var/named/chroot/` directory because it is mounted automatically. This simplifies maintenance since you do not need to take any special care of `BIND` configuration files if it is run in a **chroot** environment. You can organize everything as you would with `BIND` not running in a **chroot** environment.

The following directories are automatically mounted into `/var/named/chroot/` if they are empty in the `/var/named/chroot/` directory. They must be kept empty if you want them to be mounted into `/var/named/chroot/`:

* `/etc/named`

* `/etc/pki/dnssec-keys`

* `/run/named`

* `/var/named`

* `/usr/lib64/bind` or `/usr/lib/bind` (architecture dependent).

The following files are also mounted if the target file does not exist in `/var/named/chroot/`:

* `/etc/named.conf`

* `/etc/rndc.conf`

* `/etc/rndc.key`

* `/etc/named.rfc1912.zones`

* `/etc/named.dnssec.keys`

* `/etc/named.iscdlv.key`

* `/etc/named.root.key`

### Important

Editing files which have been mounted in a **chroot** environment requires creating a backup copy and then editing the original file. Alternatively, use an editor with “edit-a-copy” mode disabled. For example, to edit the BIND's configuration file, `/etc/named.conf`, with Vim while it is running in a **chroot** environment, issue the following command as `root`:

	~]# **vim -c "set backupcopy=yes" /etc/named.conf**

#### 10\.2.2.1. Installing BIND in a chroot Environment	{#sec-Installing_Bind_In_A_Chroot_Environment}

To install BIND to run in a **chroot** environment, issue the following command as `root`:

	~]# **yum install bind-chroot**

To enable the `named-chroot` service, first check if the `named` service is running by issuing the following command:

	~]$ **systemctl status named**

If it is running, it must be disabled.

To disable `named`, issue the following commands as `root`:

	~]# **systemctl stop named**

	~]# **systemctl disable named**

Then, to enable the `named-chroot` service, issue the following commands as `root`:

	~]# **systemctl enable named-chroot**

	~]# **systemctl start named-chroot**

To check the status of the `named-chroot` service, issue the following command as `root`:

	~]# **systemctl status named-chroot**

#### 10\.2.2.2. Common Statement Types	{#sec-bind-namedconf-state}

The following types of statements are commonly used in `/etc/named.conf`:

`acl`
:    The `acl` (Access Control List) statement allows you to define groups of hosts, so that they can be permitted or denied access to the nameserver. It takes the following form:

	acl _`acl-name`_ {
	  _`match-element`_;
	  ...
	};

The _`acl-name`_ statement name is the name of the access control list, and the _`match-element`_ option is usually an individual `IP` address (such as `10.0.1.1`) or a _Classless Inter-Domain Routing_ (CIDR) network notation (for example, `10.0.1.0/24`). For a list of already defined keywords, see [Table 10.2, “Predefined Access Control Lists”](#table-bind-namedconf-common-acl "Table 10.2. Predefined Access Control Lists").

Table 10.2. Predefined Access Control Lists

|Keyword|Description|
|-|
|`any`|Matches every `IP` address.|
|`localhost`|Matches any `IP` address that is in use by the local system.|
|`localnets`|Matches any `IP` address on any network to which the local system is connected.|
|`none`|Does not match any `IP` address.|

<br />

The `acl` statement can be especially useful in conjunction with other statements such as `options`. [Example 10.2, “Using acl in Conjunction with Options”](#example-bind-namedconf-common-acl "Example 10.2. Using acl in Conjunction with Options") defines two access control lists, `black-hats` and `red-hats`, and adds `black-hats` on the blacklist while granting `red-hats` normal access.

Example 10.2. Using acl in Conjunction with Options

	acl black-hats {
	  10.0.2.0/24;
	  192.168.0.0/24;
	  1234:5678::9abc/24;
	};
	acl red-hats {
	  10.0.1.0/24;
	};
	options {
	  blackhole { black-hats; };
	  allow-query { red-hats; };
	  allow-query-cache { red-hats; };
	};

<br />

`include`
:    The `include` statement allows you to include files in the `/etc/named.conf`, so that potentially sensitive data can be placed in a separate file with restricted permissions. It takes the following form:

	include "_`file-name`_"

The _`file-name`_ statement name is an absolute path to a file.

Example 10.3. Including a File to /etc/named.conf

	include "/etc/named.rfc1912.zones";

<br />

`options`
:    The `options` statement allows you to define global server configuration options as well as to set defaults for other statements. It can be used to specify the location of the `named` working directory, the types of queries allowed, and much more. It takes the following form:

	options {
	  _`option`_;
	  ...
	};

For a list of frequently used _`option`_ directives, see [Table 10.3, “Commonly Used Configuration Options”](#table-bind-namedconf-common-options "Table 10.3. Commonly Used Configuration Options") below.

Table 10.3. Commonly Used Configuration Options

|Option|Description|
|-|
|`allow-query`|Specifies which hosts are allowed to query the nameserver for authoritative resource records. It accepts an access control list, a collection of `IP` addresses, or networks in the CIDR notation. All hosts are allowed by default.|
|`allow-query-cache`|Specifies which hosts are allowed to query the nameserver for non-authoritative data such as recursive queries. Only `localhost` and `localnets` are allowed by default.|
|`blackhole`|Specifies which hosts are _not_ allowed to query the nameserver. This option should be used when a particular host or network floods the server with requests. The default option is `none`.|
|`directory`|Specifies a working directory for the `named` service. The default option is `/var/named/`.|
|`disable-empty-zone`|Used to disable one or more empty zones from the list of default prefixes that would be used. Can be specified in the options statement and also in view statements. It can be used multiple times.|
|`dnssec-enable`|Specifies whether to return DNSSEC related resource records. The default option is `yes`.|
|`dnssec-validation`|Specifies whether to prove that resource records are authentic via DNSSEC. The default option is `yes`.|
|`empty-zones-enable`|Controls whether or not empty zones are created. Can be specified only in the options statement.|
|`forwarders`|Specifies a list of valid `IP` addresses for nameservers to which the requests should be forwarded for resolution.|
|`forward`|Specifies the behavior of the `forwarders` directive. It accepts the following options:

* `first` — The server will query the nameservers listed in the `forwarders` directive before attempting to resolve the name on its own.

* `only` — When unable to query the nameservers listed in the `forwarders` directive, the server will not attempt to resolve the name on its own.|
|`listen-on`|Specifies the `IPv4` network interface on which to listen for queries. On a `DNS` server that also acts as a gateway, you can use this option to answer queries originating from a single network only. All `IPv4` interfaces are used by default.|
|`listen-on-v6`|Specifies the `IPv6` network interface on which to listen for queries. On a `DNS` server that also acts as a gateway, you can use this option to answer queries originating from a single network only. All `IPv6` interfaces are used by default.|
|`max-cache-size`|Specifies the maximum amount of memory to be used for server caches. When the limit is reached, the server causes records to expire prematurely so that the limit is not exceeded. In a server with multiple views, the limit applies separately to the cache of each view. The default option is `32M`.|
|`notify`|Specifies whether to notify the secondary nameservers when a zone is updated. It accepts the following options:

* `yes` — The server will notify all secondary nameservers.

* `no` — The server will _not_ notify any secondary nameserver.

* `master-only` — The server will notify primary server for the zone only.

* `explicit` — The server will notify only the secondary servers that are specified in the `also-notify` list within a zone statement.|
|`pid-file`|Specifies the location of the process ID file created by the `named` service.|
|`recursion`|Specifies whether to act as a recursive server. The default option is `yes`.|
|`statistics-file`|Specifies an alternate location for statistics files. The `/var/named/named.stats` file is used by default.|

<br />

### Note

The directory used by `named` for runtime data has been moved from the BIND default location, `/var/run/named/`, to a new location `/run/named/`. As a result, the PID file has been moved from the default location `/var/run/named/named.pid` to the new location `/run/named/named.pid`. In addition, the session-key file has been moved to `/run/named/session.key`. These locations need to be specified by statements in the options section. See [Example 10.4, “Using the options Statement”](#example-bind-namedconf-common-options "Example 10.4. Using the options Statement").

### Restrict recursive servers to selected clients only

To prevent distributed denial of service (DDoS) attacks, it is recommended that you use the `allow-query-cache` option to restrict recursive `DNS` services for a particular subset of clients only.

Refer to the _BIND 9 Administrator Reference Manual_ referenced in [Section 10.2.8.1, “Installed Documentation”](#sec-bind-installed-docs "10.2.8.1. Installed Documentation"), and the `named.conf` manual page for a complete list of available options.

Example 10.4. Using the options Statement

	options {
	  allow-query       { localhost; };
	  listen-on port    53 { 127.0.0.1; };
	  listen-on-v6 port 53 { ::1; };
	  max-cache-size    256M;
	  directory         "/var/named";
	  statistics-file   "/var/named/data/named_stats.txt";

	  recursion         yes;
	  dnssec-enable     yes;
	  dnssec-validation yes;

	  pid-file          "/run/named/named.pid";
	  session-keyfile   "/run/named/session.key";
	};

<br />

`zone`
:    The `zone` statement allows you to define the characteristics of a zone, such as the location of its configuration file and zone-specific options, and can be used to override the global `options` statements. It takes the following form:

	zone _`zone-name`_ [_`zone-class`_] {
	  _`option`_;
	  ...
	};

The _`zone-name`_ attribute is the name of the zone, _`zone-class`_ is the optional class of the zone, and _`option`_ is a `zone` statement option as described in [Table 10.4, “Commonly Used Options in Zone Statements”](#table-bind-namedconf-common-zone "Table 10.4. Commonly Used Options in Zone Statements").

The _`zone-name`_ attribute is particularly important, as it is the default value assigned for the `$ORIGIN` directive used within the corresponding zone file located in the `/var/named/` directory. The `named` daemon appends the name of the zone to any non-fully qualified domain name listed in the zone file. For example, if a `zone` statement defines the namespace for `example.com`, use `example.com` as the _`zone-name`_ so that it is placed at the end of host names within the `example.com` zone file.

For more information about zone files, refer to [Section 10.2.3, “Editing Zone Files”](#sec-bind-zone "10.2.3. Editing Zone Files").

Table 10.4. Commonly Used Options in Zone Statements

|Option|Description|
|-|
|`allow-query`|Specifies which clients are allowed to request information about this zone. This option overrides global `allow-query` option. All query requests are allowed by default.|
|`allow-transfer`|Specifies which secondary servers are allowed to request a transfer of the zone's information. All transfer requests are allowed by default.|
|`allow-update`|Specifies which hosts are allowed to dynamically update information in their zone. The default option is to deny all dynamic update requests.

Note that you should be careful when allowing hosts to update information about their zone. Do not set `IP` addresses in this option unless the server is in the trusted network. Instead, use TSIG key as described in [Section 10.2.6.3, “Transaction SIGnatures (TSIG)”](#sec-bind-features-tsig "10.2.6.3. Transaction SIGnatures (TSIG)").|
|`file`|Specifies the name of the file in the `named` working directory that contains the zone's configuration data.|
|`masters`|Specifies from which `IP` addresses to request authoritative zone information. This option is used only if the zone is defined as `type` `slave`.|
|`notify`|Specifies whether to notify the secondary nameservers when a zone is updated. It accepts the following options:

* `yes` — The server will notify all secondary nameservers.

* `no` — The server will _not_ notify any secondary nameserver.

* `master-only` — The server will notify primary server for the zone only.

* `explicit` — The server will notify only the secondary servers that are specified in the `also-notify` list within a zone statement.|
|`type`|Specifies the zone type. It accepts the following options:

* `delegation-only` — Enforces the delegation status of infrastructure zones such as COM, NET, or ORG. Any answer that is received without an explicit or implicit delegation is treated as `NXDOMAIN`. This option is only applicable in TLDs (Top-Level Domain) or root zone files used in recursive or caching implementations.

* `forward` — Forwards all requests for information about this zone to other nameservers.

* `hint` — A special type of zone used to point to the root nameservers which resolve queries when a zone is not otherwise known. No configuration beyond the default is necessary with a `hint` zone.

* `master` — Designates the nameserver as authoritative for this zone. A zone should be set as the `master` if the zone's configuration files reside on the system.

* `slave` — Designates the nameserver as a slave server for this zone. Master server is specified in `masters` directive.|

<br />

Most changes to the `/etc/named.conf` file of a primary or secondary nameserver involve adding, modifying, or deleting `zone` statements, and only a small subset of `zone` statement options is usually needed for a nameserver to work efficiently.

In [Example 10.5, “A Zone Statement for a Primary nameserver”](#example-bind-namedconf-common-zone-primary "Example 10.5. A Zone Statement for a Primary nameserver"), the zone is identified as `example.com`, the type is set to `master`, and the `named` service is instructed to read the `/var/named/example.com.zone` file. It also allows only a secondary nameserver (`192.168.0.2`) to transfer the zone.

Example 10.5. A Zone Statement for a Primary nameserver

	zone "example.com" IN {
	  type master;
	  file "example.com.zone";
	  allow-transfer { 192.168.0.2; };
	};

<br />

A secondary server's `zone` statement is slightly different. The type is set to `slave`, and the `masters` directive is telling `named` the `IP` address of the master server.

In [Example 10.6, “A Zone Statement for a Secondary nameserver”](#example-bind-namedconf-common-zone-secondary "Example 10.6. A Zone Statement for a Secondary nameserver"), the `named` service is configured to query the primary server at the `192.168.0.1` `IP` address for information about the `example.com` zone. The received information is then saved to the `/var/named/slaves/example.com.zone` file. Note that you have to put all slave zones in the `/var/named/slaves/` directory, otherwise the service will fail to transfer the zone.

Example 10.6. A Zone Statement for a Secondary nameserver

	zone "example.com" {
	  type slave;
	  file "slaves/example.com.zone";
	  masters { 192.168.0.1; };
	};

<br />

#### 10\.2.2.3. Other Statement Types	{#sec-bind-namedconf-state-other}

The following types of statements are less commonly used in `/etc/named.conf`:

`controls`
:    The `controls` statement allows you to configure various security requirements necessary to use the **rndc** command to administer the `named` service.

Refer to [Section 10.2.4, “Using the rndc Utility”](#sec-bind-rndc "10.2.4. Using the rndc Utility") for more information on the **rndc** utility and its usage.

`key`
:    The `key` statement allows you to define a particular key by name. Keys are used to authenticate various actions, such as secure updates or the use of the **rndc** command. Two options are used with `key`:

* ``algorithm _`algorithm-name`_`` — The type of algorithm to be used (for example, `hmac-md5`).

* ``secret "_`key-value`_"`` — The encrypted key.

Refer to [Section 10.2.4, “Using the rndc Utility”](#sec-bind-rndc "10.2.4. Using the rndc Utility") for more information on the **rndc** utility and its usage.

`logging`
:    The `logging` statement allows you to use multiple types of logs, so called _channels_. By using the `channel` option within the statement, you can construct a customized type of log with its own file name (`file`), size limit (`size`), version number (`version`), and level of importance (`severity`). Once a customized channel is defined, a `category` option is used to categorize the channel and begin logging when the `named` service is restarted.

By default, `named` sends standard messages to the `rsyslog` daemon, which places them in `/var/log/messages`. Several standard channels are built into BIND with various severity levels, such as `default_syslog` (which handles informational logging messages) and `default_debug` (which specifically handles debugging messages). A default category, called `default`, uses the built-in channels to do normal logging without any special configuration.

Customizing the logging process can be a very detailed process and is beyond the scope of this chapter. For information on creating custom BIND logs, refer to the _BIND 9 Administrator Reference Manual_ referenced in [Section 10.2.8.1, “Installed Documentation”](#sec-bind-installed-docs "10.2.8.1. Installed Documentation").

`server`
:    The `server` statement allows you to specify options that affect how the `named` service should respond to remote nameservers, especially with regard to notifications and zone transfers.

The `transfer-format` option controls the number of resource records that are sent with each message. It can be either `one-answer` (only one resource record), or `many-answers` (multiple resource records). Note that while the `many-answers` option is more efficient, it is not supported by older versions of BIND.

`trusted-keys`
:    The `trusted-keys` statement allows you to specify assorted public keys used for secure `DNS` (DNSSEC). Refer to [Section 10.2.6.4, “DNS Security Extensions (DNSSEC)”](#sec-bind-features-dnssec "10.2.6.4. DNS Security Extensions (DNSSEC)") for more information on this topic.

`view`
:    The `view` statement allows you to create special views depending upon which network the host querying the nameserver is on. This allows some hosts to receive one answer regarding a zone while other hosts receive totally different information. Alternatively, certain zones may only be made available to particular trusted hosts while non-trusted hosts can only make queries for other zones.

Multiple views can be used as long as their names are unique. The `match-clients` option allows you to specify the `IP` addresses that apply to a particular view. If the `options` statement is used within a view, it overrides the already configured global options. Finally, most `view` statements contain multiple `zone` statements that apply to the `match-clients` list.

Note that the order in which the `view` statements are listed is important, as the first statement that matches a particular client's `IP` address is used. For more information on this topic, refer to [Section 10.2.6.1, “Multiple Views”](#sec-bind-features-views "10.2.6.1. Multiple Views").

#### 10\.2.2.4. Comment Tags	{#sec-bind-namedconf-comm}

Additionally to statements, the `/etc/named.conf` file can also contain comments. Comments are ignored by the `named` service, but can prove useful when providing additional information to a user. The following are valid comment tags:

`//`
:    Any text after the `//` characters to the end of the line is considered a comment. For example:

	notify yes;  // notify all secondary nameservers

`#`
:    Any text after the `#` character to the end of the line is considered a comment. For example:

	notify yes;  # notify all secondary nameservers

`/*` and `*/`
:    Any block of text enclosed in `/*` and `*/` is considered a comment. For example:

	notify yes;  /* notify all secondary nameservers */

### 10\.2.3. Editing Zone Files	{#sec-bind-zone}

As outlined in [Section 10.1.1, “Nameserver Zones”](#sec-dns-introduction-zones "10.1.1. Nameserver Zones"), zone files contain information about a namespace. They are stored in the `named` working directory located in `/var/named/` by default. Each zone file is named according to the `file` option in the `zone` statement, usually in a way that relates to the domain in and identifies the file as containing zone data, such as `example.com.zone`.

Table 10.5. The named Service Zone Files

|Path|Description|
|-|
|`/var/named/`|The working directory for the `named` service. The nameserver is _not_ allowed to write to this directory.|
|`/var/named/slaves/`|The directory for secondary zones. This directory is writable by the `named` service.|
|`/var/named/dynamic/`|The directory for other files, such as dynamic `DNS` (DDNS) zones or managed DNSSEC keys. This directory is writable by the `named` service.|
|`/var/named/data/`|The directory for various statistics and debugging files. This directory is writable by the `named` service.|

<br />

A zone file consists of directives and resource records. Directives tell the nameserver to perform tasks or apply special settings to the zone, resource records define the parameters of the zone and assign identities to individual hosts. While the directives are optional, the resource records are required in order to provide name service to a zone.

All directives and resource records should be entered on individual lines.

#### 10\.2.3.1. Common Directives	{#sec-bind-zone-directives}

Directives begin with the dollar sign character (`$`) followed by the name of the directive, and usually appear at the top of the file. The following directives are commonly used in zone files:

**$INCLUDE**
:    The **$INCLUDE** directive allows you to include another file at the place where it appears, so that other zone settings can be stored in a separate zone file.

Example 10.7. Using the $INCLUDE Directive

	$INCLUDE /var/named/penguin.example.com

<br />

**$ORIGIN**
:    The **$ORIGIN** directive allows you to append the domain name to unqualified records, such as those with the host name only. Note that the use of this directive is not necessary if the zone is specified in `/etc/named.conf`, since the zone name is used by default.

In [Example 10.8, “Using the $ORIGIN Directive”](#example-bind-zone-directive-origin "Example 10.8. Using the $ORIGIN Directive"), any names used in resource records that do not end in a trailing period (the `.` character) are appended with `example.com`.

Example 10.8. Using the $ORIGIN Directive

	$ORIGIN example.com.

<br />

**$TTL**
:    The **$TTL** directive allows you to set the default _Time to Live_ (TTL) value for the zone, that is, how long is a zone record valid. Each resource record can contain its own TTL value, which overrides this directive.

Increasing this value allows remote nameservers to cache the zone information for a longer period of time, reducing the number of queries for the zone and lengthening the amount of time required to propagate resource record changes.

Example 10.9. Using the $TTL Directive

	$TTL 1D

<br />

#### 10\.2.3.2. Common Resource Records	{#sec-bind-zone-rr}

The following resource records are commonly used in zone files:

**A**
:    The _Address_ record specifies an `IP` address to be assigned to a name. It takes the following form:

	_`hostname`_ IN A _`IP-address`_

If the _`hostname`_ value is omitted, the record will point to the last specified _`hostname`_.

In [Example 10.10, “Using the A Resource Record”](#example-bind-zone-rr-a "Example 10.10. Using the A Resource Record"), the requests for `server1.example.com` are pointed to `10.0.1.3` or `10.0.1.5`.

Example 10.10. Using the A Resource Record

	server1  IN  A  10.0.1.3
	         IN  A  10.0.1.5

<br />

**CNAME**
:    The _Canonical Name_ record maps one name to another. Because of this, this type of record is sometimes referred to as an _alias record_. It takes the following form:

	_`alias-name`_ IN CNAME _`real-name`_

**CNAME** records are most commonly used to point to services that use a common naming scheme, such as `www` for Web servers. However, there are multiple restrictions for their usage:

* CNAME records should not point to other CNAME records. This is mainly to avoid possible infinite loops.

* CNAME records should not contain other resource record types (such as A, NS, MX, etc.). The only exception are DNSSEC related records (RRSIG, NSEC, etc.) when the zone is signed.

* Other resource records that point to the fully qualified domain name (FQDN) of a host (NS, MX, PTR) should not point to a CNAME record.

In [Example 10.11, “Using the CNAME Resource Record”](#example-bind-zone-rr-cname "Example 10.11. Using the CNAME Resource Record"), the **A** record binds a host name to an `IP` address, while the **CNAME** record points the commonly used `www` host name to it.

Example 10.11. Using the CNAME Resource Record

	server1  IN  A      10.0.1.5
	www      IN  CNAME  server1

<br />

**MX**
:    The _Mail Exchange_ record specifies where the mail sent to a particular namespace controlled by this zone should go. It takes the following form:

	IN MX _`preference-value`_ _`email-server-name`_

The _`email-server-name`_ is a fully qualified domain name (FQDN). The _`preference-value`_ allows numerical ranking of the email servers for a namespace, giving preference to some email systems over others. The **MX** resource record with the lowest _`preference-value`_ is preferred over the others. However, multiple email servers can possess the same value to distribute email traffic evenly among them.

In [Example 10.12, “Using the MX Resource Record”](#example-bind-zone-rr-mx "Example 10.12. Using the MX Resource Record"), the first `mail.example.com` email server is preferred to the `mail2.example.com` email server when receiving email destined for the `example.com` domain.

Example 10.12. Using the MX Resource Record

	example.com.  IN  MX  10  mail.example.com.
	              IN  MX  20  mail2.example.com.

<br />

**NS**
:    The _Nameserver_ record announces authoritative nameservers for a particular zone. It takes the following form:

	IN NS _`nameserver-name`_

The _`nameserver-name`_ should be a fully qualified domain name (FQDN). Note that when two nameservers are listed as authoritative for the domain, it is not important whether these nameservers are secondary nameservers, or if one of them is a primary server. They are both still considered authoritative.

Example 10.13. Using the NS Resource Record

	IN  NS  dns1.example.com.
	IN  NS  dns2.example.com.

<br />

**PTR**
:    The _Pointer_ record points to another part of the namespace. It takes the following form:

	_`last-IP-digit`_ IN PTR _`FQDN-of-system`_

The _`last-IP-digit`_ directive is the last number in an `IP` address, and the _`FQDN-of-system`_ is a fully qualified domain name (FQDN).

**PTR** records are primarily used for reverse name resolution, as they point `IP` addresses back to a particular name. Refer to [Section 10.2.3.4.2, “A Reverse Name Resolution Zone File”](#sec-bind-configuration-zone-reverse "10.2.3.4.2. A Reverse Name Resolution Zone File") for examples of **PTR** records in use.

**SOA**
:    The _Start of Authority_ record announces important authoritative information about a namespace to the nameserver. Located after the directives, it is the first resource record in a zone file. It takes the following form:

	@  IN  SOA  _`primary-name-server`_ _`hostmaster-email`_ (
	       _`serial-number`_
	       _`time-to-refresh`_
	       _`time-to-retry`_
	       _`time-to-expire`_
	       _`minimum-TTL`_ )

The directives are as follows:

* The `@` symbol places the **$ORIGIN** directive (or the zone's name if the **$ORIGIN** directive is not set) as the namespace being defined by this **SOA** resource record.

* The _`primary-name-server`_ directive is the host name of the primary nameserver that is authoritative for this domain.

* The _`hostmaster-email`_ directive is the email of the person to contact about the namespace.

* The _`serial-number`_ directive is a numerical value incremented every time the zone file is altered to indicate it is time for the `named` service to reload the zone.

* The _`time-to-refresh`_ directive is the numerical value secondary nameservers use to determine how long to wait before asking the primary nameserver if any changes have been made to the zone.

* The _`time-to-retry`_ directive is a numerical value used by secondary nameservers to determine the length of time to wait before issuing a refresh request in the event that the primary nameserver is not answering. If the primary server has not replied to a refresh request before the amount of time specified in the _`time-to-expire`_ directive elapses, the secondary servers stop responding as an authority for requests concerning that namespace.

* In BIND 4 and 8, the _`minimum-TTL`_ directive is the amount of time other nameservers cache the zone's information. In BIND 9, it defines how long negative answers are cached for. Caching of negative answers can be set to a maximum of 3 hours (`3H`).

When configuring BIND, all times are specified in seconds. However, it is possible to use abbreviations when specifying units of time other than seconds, such as minutes (`M`), hours (`H`), days (`D`), and weeks (`W`). [Table 10.6, “Seconds compared to other time units”](#tb-bind-seconds "Table 10.6. Seconds compared to other time units") shows an amount of time in seconds and the equivalent time in another format.

Table 10.6. Seconds compared to other time units

|Seconds|Other Time Units|
|-|
|60|`1M`|
|1800|`30M`|
|3600|`1H`|
|10800|`3H`|
|21600|`6H`|
|43200|`12H`|
|86400|`1D`|
|259200|`3D`|
|604800|`1W`|
|31536000|`365D`|

<br />

Example 10.14. Using the SOA Resource Record

	@  IN  SOA  dns1.example.com.  hostmaster.example.com. (
	       2001062501  ; serial
	       21600       ; refresh after 6 hours
	       3600        ; retry after 1 hour
	       604800      ; expire after 1 week
	       86400 )     ; minimum TTL of 1 day

<br />

#### 10\.2.3.3. Comment Tags	{#sec-bind-zone-comm}

Additionally to resource records and directives, a zone file can also contain comments. Comments are ignored by the `named` service, but can prove useful when providing additional information to the user. Any text after the semicolon character (`;`) to the end of the line is considered a comment. For example:

	   604800  ; expire after 1 week

#### 10\.2.3.4. Example Usage	{#sec-bind-zone-examples}

The following examples show the basic usage of zone files.

##### 10\.2.3.4.1. A Simple Zone File	{#sec-bind-zone-examples-basic}

[Example 10.15, “A simple zone file”](#example-bind-zone-examples-basic "Example 10.15. A simple zone file") demonstrates the use of standard directives and **SOA** values.

Example 10.15. A simple zone file

	$ORIGIN example.com.
	$TTL 86400
	@         IN  SOA  dns1.example.com.  hostmaster.example.com. (
	              2001062501  ; serial
	              21600       ; refresh after 6 hours
	              3600        ; retry after 1 hour
	              604800      ; expire after 1 week
	              86400 )     ; minimum TTL of 1 day
	;
	;
	          IN  NS     dns1.example.com.
	          IN  NS     dns2.example.com.
	dns1      IN  A      10.0.1.1
	          IN  AAAA   aaaa:bbbb::1
	dns2      IN  A      10.0.1.2
	          IN  AAAA   aaaa:bbbb::2
	;
	;
	@         IN  MX     10  mail.example.com.
	          IN  MX     20  mail2.example.com.
	mail      IN  A      10.0.1.5
	          IN  AAAA   aaaa:bbbb::5
	mail2     IN  A      10.0.1.6
	          IN  AAAA   aaaa:bbbb::6
	;
	;
	; This sample zone file illustrates sharing the same IP addresses
	; for multiple services:
	;
	services  IN  A      10.0.1.10
	          IN  AAAA   aaaa:bbbb::10
	          IN  A      10.0.1.11
	          IN  AAAA   aaaa:bbbb::11

	ftp       IN  CNAME  services.example.com.
	www       IN  CNAME  services.example.com.
	;
	;

<br />

In this example, the authoritative nameservers are set as `dns1.example.com` and `dns2.example.com`, and are tied to the `10.0.1.1` and `10.0.1.2` `IP` addresses respectively using the **A** record.

The email servers configured with the **MX** records point to `mail` and `mail2` via **A** records. Since these names do not end in a trailing period (`.` character), the **$ORIGIN** domain is placed after them, expanding them to `mail.example.com` and `mail2.example.com`.

Services available at the standard names, such as `www.example.com` (WWW), are pointed at the appropriate servers using the **CNAME** record.

This zone file would be called into service with a **zone** statement in the `/etc/named.conf` similar to the following:

	zone "example.com" IN {
	  type master;
	  file "example.com.zone";
	  allow-update { none; };
	};

##### 10\.2.3.4.2. A Reverse Name Resolution Zone File	{#sec-bind-configuration-zone-reverse}

A reverse name resolution zone file is used to translate an `IP` address in a particular namespace into a fully qualified domain name (FQDN). It looks very similar to a standard zone file, except that the **PTR** resource records are used to link the `IP` addresses to a fully qualified domain name as shown in [Example 10.16, “A reverse name resolution zone file”](#example-bind-zone-examples-reverse "Example 10.16. A reverse name resolution zone file").

Example 10.16. A reverse name resolution zone file

	$ORIGIN 1.0.10.in-addr.arpa.
	$TTL 86400
	@  IN  SOA  dns1.example.com.  hostmaster.example.com. (
	       2001062501  ; serial
	       21600       ; refresh after 6 hours
	       3600        ; retry after 1 hour
	       604800      ; expire after 1 week
	       86400 )     ; minimum TTL of 1 day
	;
	@  IN  NS   dns1.example.com.
	;
	1  IN  PTR  dns1.example.com.
	2  IN  PTR  dns2.example.com.
	;
	5  IN  PTR  server1.example.com.
	6  IN  PTR  server2.example.com.
	;
	3  IN  PTR  ftp.example.com.
	4  IN  PTR  ftp.example.com.

<br />

In this example, `IP` addresses `10.0.1.1` through `10.0.1.6` are pointed to the corresponding fully qualified domain name.

This zone file would be called into service with a `zone` statement in the `/etc/named.conf` file similar to the following:

	zone "1.0.10.in-addr.arpa" IN {
	  type master;
	  file "example.com.rr.zone";
	  allow-update { none; };
	};

There is very little difference between this example and a standard **zone** statement, except for the zone name. Note that a reverse name resolution zone requires the first three blocks of the `IP` address reversed followed by **.in-addr.arpa**. This allows the single block of `IP` numbers used in the reverse name resolution zone file to be associated with the zone.

### 10\.2.4. Using the rndc Utility	{#sec-bind-rndc}

The **rndc** utility is a command-line tool that allows you to administer the `named` service, both locally and from a remote machine. Its usage is as follows:

	**rndc** [_`option`_...] _`command`_ [_`command-option`_]

#### 10\.2.4.1. Configuring the Utility	{#sec-bind-rndc-configuration}

To prevent unauthorized access to the service, `named` must be configured to listen on the selected port (`953` by default), and an identical key must be used by both the service and the **rndc** utility.

Table 10.7. Relevant files

|Path|Description|
|-|
|`/etc/named.conf`|The default configuration file for the `named` service.|
|`/etc/rndc.conf`|The default configuration file for the **rndc** utility.|
|`/etc/rndc.key`|The default key location.|

<br />

The **rndc** configuration is located in `/etc/rndc.conf`. If the file does not exist, the utility will use the key located in `/etc/rndc.key`, which was generated automatically during the installation process using the **rndc-confgen -a** command.

The `named` service is configured using the `controls` statement in the `/etc/named.conf` configuration file as described in [Section 10.2.2.3, “Other Statement Types”](#sec-bind-namedconf-state-other "10.2.2.3. Other Statement Types"). Unless this statement is present, only the connections from the loopback address (`127.0.0.1`) will be allowed, and the key located in `/etc/rndc.key` will be used.

For more information on this topic, refer to manual pages and the _BIND 9 Administrator Reference Manual_ listed in [Section 10.2.8, “Additional Resources”](#sec-bind-additional-resources "10.2.8. Additional Resources").

### Set the correct permissions

To prevent unprivileged users from sending control commands to the service, make sure only `root` is allowed to read the `/etc/rndc.key` file:

	~]# **chmod o-rwx /etc/rndc.key**

#### 10\.2.4.2. Checking the Service Status	{#sec-bind-rndc-status}

To check the current status of the `named` service, use the following command:

	~]# **rndc status**
	version: 9.7.0-P2-RedHat-9.7.0-5.P2.el6
	CPUs found: 1
	worker threads: 1
	number of zones: 16
	debug level: 0
	xfers running: 0
	xfers deferred: 0
	soa queries in progress: 0
	query logging is OFF
	recursive clients: 0/0/1000
	tcp clients: 0/100
	server is up and running

#### 10\.2.4.3. Reloading the Configuration and Zones	{#sec-bind-rndc-reload}

To reload both the configuration file and zones, type the following at a shell prompt:

	~]# **rndc reload**
	server reload successful

This will reload the zones while keeping all previously cached responses, so that you can make changes to the zone files without losing all stored name resolutions.

To reload a single zone, specify its name after the **reload** command, for example:

	~]# **rndc reload localhost**
	zone reload up-to-date

Finally, to reload the configuration file and newly added zones only, type:

	~]# **rndc reconfig**

### Modifying zones with dynamic DNS

If you intend to manually modify a zone that uses Dynamic `DNS` (DDNS), make sure you run the **freeze** command first:

	~]# **rndc freeze localhost**

Once you are finished, run the **thaw** command to allow the `DDNS` again and reload the zone:

	~]# **rndc thaw localhost**
	The zone reload and thaw was successful.

#### 10\.2.4.4. Updating Zone Keys	{#sec-bind-rndc-sign}

To update the DNSSEC keys and sign the zone, use the **sign** command. For example:

	~]# **rndc sign localhost**

Note that to sign a zone with the above command, the `auto-dnssec` option has to be set to `maintain` in the zone statement. For example:

	zone "localhost" IN {
	  type master;
	  file "named.localhost";
	  allow-update { none; };
	  auto-dnssec maintain;
	};

#### 10\.2.4.5. Enabling the DNSSEC Validation	{#sec-bind-rndc-validation}

To enable the DNSSEC validation, issue the following command as `root`:

	~]# **rndc validation on**

Similarly, to disable this option, type:

	~]# **rndc validation off**

Refer to the `options` statement described in [Section 10.2.2.2, “Common Statement Types”](#sec-bind-namedconf-state "10.2.2.2. Common Statement Types") for information on how to configure this option in `/etc/named.conf`.

#### 10\.2.4.6. Enabling the Query Logging	{#sec-bind-rndc-querylog}

To enable (or disable in case it is currently enabled) the query logging, issue the following command as `root`:

	~]# **rndc querylog**

To check the current setting, use the **status** command as described in [Section 10.2.4.2, “Checking the Service Status”](#sec-bind-rndc-status "10.2.4.2. Checking the Service Status").

### 10\.2.5. Using the dig Utility	{#sec-bind-dig}

The **dig** utility is a command-line tool that allows you to perform `DNS` lookups and debug a nameserver configuration. Its typical usage is as follows:

	**dig** [@_`server`_] [_`option`_...] _`name`_ _`type`_

Refer to [Section 10.2.3.2, “Common Resource Records”](#sec-bind-zone-rr "10.2.3.2. Common Resource Records") for a list of common values to use for _`type`_.

#### 10\.2.5.1. Looking Up a Nameserver	{#sec-bind-dig-ns}

To look up a nameserver for a particular domain, use the command in the following form:

	**dig** _`name`_ NS

In [Example 10.17, “A sample nameserver lookup”](#example-bind-dig-ns "Example 10.17. A sample nameserver lookup"), the **dig** utility is used to display nameservers for `example.com`.

Example 10.17. A sample nameserver lookup

	~]$ **dig example.com NS**

	; &lt;&lt;&gt;&gt; DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 &lt;&lt;&gt;&gt; example.com NS
	;; global options: +cmd
	;; Got answer:
	;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 57883
	;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

	;; QUESTION SECTION:
	;example.com.                   IN      NS

	;; ANSWER SECTION:
	example.com.            99374   IN      NS      a.iana-servers.net.
	example.com.            99374   IN      NS      b.iana-servers.net.

	;; Query time: 1 msec
	;; SERVER: 10.34.255.7#53(10.34.255.7)
	;; WHEN: Wed Aug 18 18:04:06 2010
	;; MSG SIZE  rcvd: 77

<br />

#### 10\.2.5.2. Looking Up an IP Address	{#sec-bind-dig-a}

To look up an `IP` address assigned to a particular domain, use the command in the following form:

	**dig** _`name`_ A

In [Example 10.18, “A sample IP address lookup”](#example-bind-dig-a "Example 10.18. A sample IP address lookup"), the **dig** utility is used to display the `IP` address of `example.com`.

Example 10.18. A sample IP address lookup

	~]$ **dig example.com A**

	; &lt;&lt;&gt;&gt; DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 &lt;&lt;&gt;&gt; example.com A
	;; global options: +cmd
	;; Got answer:
	;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 4849
	;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 0

	;; QUESTION SECTION:
	;example.com.                   IN      A

	;; ANSWER SECTION:
	example.com.            155606  IN      A       192.0.32.10

	;; AUTHORITY SECTION:
	example.com.            99175   IN      NS      a.iana-servers.net.
	example.com.            99175   IN      NS      b.iana-servers.net.

	;; Query time: 1 msec
	;; SERVER: 10.34.255.7#53(10.34.255.7)
	;; WHEN: Wed Aug 18 18:07:25 2010
	;; MSG SIZE  rcvd: 93

<br />

#### 10\.2.5.3. Looking Up a Host Name	{#sec-bind-dig-x}

To look up a host name for a particular `IP` address, use the command in the following form:

	**dig** `-x` _`address`_

In [Example 10.19, “A Sample Host Name Lookup”](#example-bind-dig-x "Example 10.19. A Sample Host Name Lookup"), the **dig** utility is used to display the host name assigned to `192.0.32.10`.

Example 10.19. A Sample Host Name Lookup

	~]$ **dig -x 192.0.32.10**

	; &lt;&lt;&gt;&gt; DiG 9.7.1-P2-RedHat-9.7.1-2.P2.fc13 &lt;&lt;&gt;&gt; -x 192.0.32.10
	;; global options: +cmd
	;; Got answer:
	;; -&gt;&gt;HEADER&lt;&lt;- opcode: QUERY, status: NOERROR, id: 29683
	;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 6

	;; QUESTION SECTION:
	;10.32.0.192.in-addr.arpa.      IN      PTR

	;; ANSWER SECTION:
	10.32.0.192.in-addr.arpa. 21600 IN      PTR     www.example.com.

	;; AUTHORITY SECTION:
	32.0.192.in-addr.arpa.  21600   IN      NS      b.iana-servers.org.
	32.0.192.in-addr.arpa.  21600   IN      NS      c.iana-servers.net.
	32.0.192.in-addr.arpa.  21600   IN      NS      d.iana-servers.net.
	32.0.192.in-addr.arpa.  21600   IN      NS      ns.icann.org.
	32.0.192.in-addr.arpa.  21600   IN      NS      a.iana-servers.net.

	;; ADDITIONAL SECTION:
	a.iana-servers.net.     13688   IN      A       192.0.34.43
	b.iana-servers.org.     5844    IN      A       193.0.0.236
	b.iana-servers.org.     5844    IN      AAAA    2001:610:240:2::c100:ec
	c.iana-servers.net.     12173   IN      A       139.91.1.10
	c.iana-servers.net.     12173   IN      AAAA    2001:648:2c30::1:10
	ns.icann.org.           12884   IN      A       192.0.34.126

	;; Query time: 156 msec
	;; SERVER: 10.34.255.7#53(10.34.255.7)
	;; WHEN: Wed Aug 18 18:25:15 2010
	;; MSG SIZE  rcvd: 310

<br />

### 10\.2.6. Advanced Features of BIND	{#sec-bind-features}

Most BIND implementations only use the `named` service to provide name resolution services or to act as an authority for a particular domain. However, BIND version 9 has a number of advanced features that allow for a more secure and efficient `DNS` service.

### Make sure the feature is supported

Before attempting to use advanced features like DNSSEC, TSIG, or IXFR (Incremental Zone Transfer), make sure that the particular feature is supported by all nameservers in the network environment, especially when you use older versions of BIND or non-BIND servers.

All of the features mentioned are discussed in greater detail in the _BIND 9 Administrator Reference Manual_ referenced in [Section 10.2.8.1, “Installed Documentation”](#sec-bind-installed-docs "10.2.8.1. Installed Documentation").

#### 10\.2.6.1. Multiple Views	{#sec-bind-features-views}

Optionally, different information can be presented to a client depending on the network a request originates from. This is primarily used to deny sensitive `DNS` entries from clients outside of the local network, while allowing queries from clients inside the local network.

To configure multiple views, add the **view** statement to the `/etc/named.conf` configuration file. Use the `match-clients` option to match `IP` addresses or entire networks and give them special options and zone data.

#### 10\.2.6.2. Incremental Zone Transfers (IXFR)	{#sec-bind-features-ixfr}

_Incremental Zone Transfers_ (_IXFR_) allow a secondary nameserver to only download the updated portions of a zone modified on a primary nameserver. Compared to the standard transfer process, this makes the notification and update process much more efficient.

Note that IXFR is only available when using dynamic updating to make changes to master zone records. If manually editing zone files to make changes, _Automatic Zone Transfer_ (_AXFR_) is used.

#### 10\.2.6.3. Transaction SIGnatures (TSIG)	{#sec-bind-features-tsig}

_Transaction SIGnatures_ (TSIG) ensure that a shared secret key exists on both primary and secondary nameservers before allowing a transfer. This strengthens the standard `IP` address-based method of transfer authorization, since attackers would not only need to have access to the `IP` address to transfer the zone, but they would also need to know the secret key.

Since version 9, BIND also supports _TKEY_, which is another shared secret key method of authorizing zone transfers.

### Secure the transfer

When communicating over an insecure network, do not rely on `IP` address-based authentication only.

#### 10\.2.6.4. DNS Security Extensions (DNSSEC)	{#sec-bind-features-dnssec}

_Domain Name System Security Extensions_ (_DNSSEC_) provide origin authentication of `DNS` data, authenticated denial of existence, and data integrity. When a particular domain is marked as secure, the `SERVFAIL` response is returned for each resource record that fails the validation.

Note that to debug a DNSSEC-signed domain or a DNSSEC-aware resolver, you can use the **dig** utility as described in [Section 10.2.5, “Using the dig Utility”](#sec-bind-dig "10.2.5. Using the dig Utility"). Useful options are `+dnssec` (requests DNSSEC-related resource records by setting the DNSSEC OK bit), `+cd` (tells recursive nameserver not to validate the response), and `+bufsize=512` (changes the packet size to 512B to get through some firewalls).

#### 10\.2.6.5. Internet Protocol version 6 (IPv6)	{#sec-bind-features-ipv6}

_Internet Protocol version 6_ (_IPv6_) is supported through the use of `AAAA` resource records, and the `listen-on-v6` directive as described in [Table 10.3, “Commonly Used Configuration Options”](#table-bind-namedconf-common-options "Table 10.3. Commonly Used Configuration Options").

### 10\.2.7. Common Mistakes to Avoid	{#sec-bind-mistakes}

The following is a list of recommendations on how to avoid common mistakes users make when configuring a nameserver:

Use semicolons and curly brackets correctly
:    An omitted semicolon or unmatched curly bracket in the `/etc/named.conf` file can prevent the `named` service from starting.

Use period (the `.` character) correctly
:    In zone files, a period at the end of a domain name denotes a fully qualified domain name. If omitted, the `named` service will append the name of the zone or the value of `$ORIGIN` to complete it.

Increment the serial number when editing a zone file
:    If the serial number is not incremented, the primary nameserver will have the correct, new information, but the secondary nameservers will never be notified of the change, and will not attempt to refresh their data of that zone.

Configure the firewall
:    If a firewall is blocking connections from the `named` service to other nameservers, the recommended practice is to change the firewall settings.

### Avoid using fixed UDP source ports	{#warning-Warning-Avoid_Using_Fixed_UDP_Source_Ports}

Using a fixed `UDP` source port for `DNS` queries is a potential security vulnerability that could allow an attacker to conduct cache-poisoning attacks more easily. To prevent this, by default `DNS` sends from a random ephemeral port. Configure your firewall to allow outgoing queries from a random `UDP` source port. The range `1024` to `65535` is used by default.

### 10\.2.8. Additional Resources	{#sec-bind-additional-resources}

The following sources of information provide additional resources regarding BIND.

#### 10\.2.8.1. Installed Documentation	{#sec-bind-installed-docs}

BIND features a full range of installed documentation covering many different topics, each placed in its own subject directory. For each item below, replace _`version`_ with the version of the bind package installed on the system:

``/usr/share/doc/bind-_`version`_/``
:    The main directory containing the most recent documentation. The directory contains the _BIND 9 Administrator Reference Manual_ in HTML and PDF formats, which details BIND resource requirements, how to configure different types of nameservers, how to perform load balancing, and other advanced topics.

``/usr/share/doc/bind-_`version`_/sample/etc/``
:    The directory containing examples of `named` configuration files.

`rndc(8)`
:    The manual page for the **rndc** name server control utility, containing documentation on its usage.

`named(8)`
:    The manual page for the Internet domain name server `named`, containing documentation on assorted arguments that can be used to control the BIND nameserver daemon.

`lwresd(8)`
:    The manual page for the lightweight resolver daemon `lwresd`, containing documentation on the daemon and its usage.

`named.conf(5)`
:    The manual page with a comprehensive list of options available within the `named` configuration file.

**rndc.conf(5)**
:    The manual page with a comprehensive list of options available within the **rndc** configuration file.

#### 10\.2.8.2. Useful Websites	{#sec-bind-useful-websites}

<http://www.isc.org/software/bind>
:    The home page of the BIND project containing information about current releases as well as a PDF version of the _BIND 9 Administrator Reference Manual_.

#### 10\.2.8.3. Related Books	{#sec-bind-related-books}

_DNS and BIND_ by Paul Albitz and Cricket Liu; O'Reilly &amp; Associates
:    A popular reference that explains both common and esoteric BIND configuration options, and provides strategies for securing a DNS server.

_The Concise Guide to DNS and BIND_ by Nicolai Langfeldt; Que
:    Looks at the connection between multiple network services and BIND, with an emphasis on task-oriented, technical topics.

# Appendix A. Revision History	{#app-Revision_History}

|**Revision History**|
|Revision 1-1|Fri Aug 1 2014|Stephen Wadeley|
||First version of the Fedora Networking Guide.||

# Index	{#idm9684896}

### Symbols

/etc/named.conf (see BIND)

/etc/sysconfig/dhcpd , [Starting and Stopping the Server](#idp4000176)

### A

authoritative nameserver (see BIND)

### B

Berkeley Internet Name Domain (see BIND)

BIND
:    additional resources
:    installed documentation, [Installed Documentation](#sec-bind-installed-docs)

related books, [Related Books](#sec-bind-related-books)

useful websites, [Useful Websites](#sec-bind-useful-websites)

common mistakes, [Common Mistakes to Avoid](#sec-bind-mistakes)

configuration
:    acl statement, [Common Statement Types](#sec-bind-namedconf-state)

comment tags, [Comment Tags](#sec-bind-namedconf-comm)

controls statement, [Other Statement Types](#sec-bind-namedconf-state-other)

include statement, [Common Statement Types](#sec-bind-namedconf-state)

key statement, [Other Statement Types](#sec-bind-namedconf-state-other)

logging statement, [Other Statement Types](#sec-bind-namedconf-state-other)

options statement, [Common Statement Types](#sec-bind-namedconf-state)

server statement, [Other Statement Types](#sec-bind-namedconf-state-other)

trusted-keys statement, [Other Statement Types](#sec-bind-namedconf-state-other)

view statement, [Other Statement Types](#sec-bind-namedconf-state-other)

zone statement, [Common Statement Types](#sec-bind-namedconf-state)

directories
:    /etc/named/, [Configuring the named Service](#sec-bind-namedconf)

/var/named/, [Editing Zone Files](#sec-bind-zone)

/var/named/data/, [Editing Zone Files](#sec-bind-zone)

/var/named/dynamic/, [Editing Zone Files](#sec-bind-zone)

/var/named/slaves/, [Editing Zone Files](#sec-bind-zone)

features
:    Automatic Zone Transfer (AXFR), [Incremental Zone Transfers (IXFR)](#sec-bind-features-ixfr)

DNS Security Extensions (DNSSEC), [DNS Security Extensions (DNSSEC)](#sec-bind-features-dnssec)

Incremental Zone Transfer (IXFR), [Incremental Zone Transfers (IXFR)](#sec-bind-features-ixfr)

Internet Protocol version 6 (IPv6), [Internet Protocol version 6 (IPv6)](#sec-bind-features-ipv6)

multiple views, [Multiple Views](#sec-bind-features-views)

Transaction SIGnature (TSIG), [Transaction SIGnatures (TSIG)](#sec-bind-features-tsig)

files
:    /etc/named.conf, [Configuring the named Service](#sec-bind-namedconf), [Configuring the Utility](#sec-bind-rndc-configuration)

/etc/rndc.conf, [Configuring the Utility](#sec-bind-rndc-configuration)

/etc/rndc.key, [Configuring the Utility](#sec-bind-rndc-configuration)

resource record, [Nameserver Zones](#sec-dns-introduction-zones)

types
:    authoritative nameserver, [Nameserver Types](#sec-dns-introduction-nameservers)

primary (master) nameserver, [Nameserver Zones](#sec-dns-introduction-zones), [Nameserver Types](#sec-dns-introduction-nameservers)

recursive nameserver, [Nameserver Types](#sec-dns-introduction-nameservers)

secondary (slave) nameserver, [Nameserver Zones](#sec-dns-introduction-zones), [Nameserver Types](#sec-dns-introduction-nameservers)

utilities
:    dig, [BIND as a Nameserver](#sec-dns-introduction-bind), [Using the dig Utility](#sec-bind-dig), [DNS Security Extensions (DNSSEC)](#sec-bind-features-dnssec)

named, [BIND as a Nameserver](#sec-dns-introduction-bind), [Configuring the named Service](#sec-bind-namedconf)

rndc, [BIND as a Nameserver](#sec-dns-introduction-bind), [Using the rndc Utility](#sec-bind-rndc)

zones
:    $INCLUDE directive, [Common Directives](#sec-bind-zone-directives)

$ORIGIN directive, [Common Directives](#sec-bind-zone-directives)

$TTL directive, [Common Directives](#sec-bind-zone-directives)

A (Address) resource record, [Common Resource Records](#sec-bind-zone-rr)

CNAME (Canonical Name) resource record, [Common Resource Records](#sec-bind-zone-rr)

comment tags, [Comment Tags](#sec-bind-zone-comm)

description, [Nameserver Zones](#sec-dns-introduction-zones)

example usage, [A Simple Zone File](#sec-bind-zone-examples-basic), [A Reverse Name Resolution Zone File](#sec-bind-configuration-zone-reverse)

MX (Mail Exchange) resource record, [Common Resource Records](#sec-bind-zone-rr)

NS (Nameserver) resource record, [Common Resource Records](#sec-bind-zone-rr)

PTR (Pointer) resource record, [Common Resource Records](#sec-bind-zone-rr)

SOA (Start of Authority) resource record, [Common Resource Records](#sec-bind-zone-rr)

bonding (see channel bonding)

### C

channel bonding
:    configuration, [Using Channel Bonding](#sec-Using_Channel_Bonding)

description, [Using Channel Bonding](#sec-Using_Channel_Bonding)

parameters to bonded interfaces, [Bonding Module Directives](#s3-modules-bonding-directives)

channel bonding interface (see kernel module)

### D

default gateway, [Static Routes and the Default Gateway](#sec-Static-Routes_and_the_Default_Gateway)

DHCP, [DHCP Servers](#ch-DHCP_Servers)
:    additional resources, [Additional Resources](#sec-dhcp-additional-resources)

command-line options, [Starting and Stopping the Server](#idp4000176)

dhcpd.conf, [Configuration File](#config-file)

dhcpd.leases, [Starting and Stopping the Server](#idp4000176)

dhcpd6.conf, [DHCP for IPv6 (DHCPv6)](#sec-dhcp_for_ipv6_dhcpv6)

DHCPv6, [DHCP for IPv6 (DHCPv6)](#sec-dhcp_for_ipv6_dhcpv6)

dhcrelay, [DHCP Relay Agent](#dhcp-relay-agent)

global parameters, [Configuration File](#config-file)

group, [Configuration File](#config-file)

options, [Configuration File](#config-file)

reasons for using, [Why Use DHCP?](#sec-dhcp-why)

Relay Agent, [DHCP Relay Agent](#dhcp-relay-agent)

server configuration, [Configuring a DHCP Server](#sec-dhcp-configuring-server)

shared-network, [Configuration File](#config-file)

starting the server, [Starting and Stopping the Server](#idp4000176)

stopping the server, [Starting and Stopping the Server](#idp4000176)

subnet, [Configuration File](#config-file)

dhcpd.conf, [Configuration File](#config-file)

dhcpd.leases, [Starting and Stopping the Server](#idp4000176)

dhcrelay, [DHCP Relay Agent](#dhcp-relay-agent)

dig (see BIND)

DNS
:    definition, [DNS Servers](#ch-DNS_Servers)
:    (see also BIND)

Dynamic Host Configuration Protocol (see DHCP)

### F

feedback
:    contact information for this manual, [Feedback](#sec-Preface-Feedback)

### K

kernel module
:    bonding module, [Using Channel Bonding](#sec-Using_Channel_Bonding)
:    description, [Using Channel Bonding](#sec-Using_Channel_Bonding)

parameters to bonded interfaces, [Bonding Module Directives](#s3-modules-bonding-directives)

module parameters
:    bonding module parameters, [Bonding Module Directives](#s3-modules-bonding-directives)

### M

Multihomed DHCP
:    host configuration, [Host Configuration](#sec-dns_Host_Configuration)

server configuration, [Configuring a Multihomed DHCP Server](#sec-Configuring_a_Multihomed_DHCP_Server)

### N

named (see BIND)

nameserver (see DNS)

NIC
:    binding into single channel, [Using Channel Bonding](#sec-Using_Channel_Bonding)

### P

primary nameserver (see BIND)

### R

recursive nameserver (see BIND)

resource record (see BIND)

rndc (see BIND)

root nameserver (see BIND)

### S

secondary nameserver (see BIND)

static route, [Static Routes and the Default Gateway](#sec-Static-Routes_and_the_Default_Gateway)

  [1]: images/Network-Wired_Gnome3.png
  [2]: images/Network-Details-Wired_Gnome3.png
  [3]: images/Editing-Bridge-Connection-1_Gnome3.png