14.15. Configure the Firewall to Allow Incoming NTP Packets
The NTP traffic consists of UDP packets on port 123 and needs to be permitted through network and host-based firewalls in order for NTP to function.
Check if the firewall is configured to allow incoming NTP traffic for clients using the graphical Firewall Configuration tool.
To start the graphical firewall-config tool, press the Super key to enter the Activities Overview, type firewall and then press Enter. The firewall-config tool appears. You will be prompted for your user password.
To start the graphical firewall configuration tool using the command line, enter the following command as
root user:
~]# firewall-config
The
Firewall Configuration window opens. Note, this command can be run as normal user but you will then be prompted for the
root password from time to time.
Look for the word “Connected” in the lower left corner. This indicates that the firewall-config tool is connected to the user space daemon, firewalld.
14.15.1. Change the Firewall Settings
To immediately change the current firewall settings, ensure the current view is set to Runtime Configuration. Alternatively, to edit the settings to be applied at the next system start, or firewall reload, select Permanent Configuration from the drop-down list.
When making changes to the firewall settings in Runtime Configuration mode, your selection takes immediate effect when you set or clear the check box associated with the service. You should keep this in mind when working on a system that may be in use by other users.
When making changes to the firewall settings in Permanent Configuration mode, your selection will only take effect when you reload the firewall or the system restarts. You can use the reload icon below the File menu, or click the Options menu and select Reload Firewall.
