14.17.5. Adding a Broadcast or Multicast Server Address
To add a broadcast or multicast address for sending, that is to say, the address to broadcast or multicast NTP
packets to, make use of the broadcast
command in the ntp.conf
file.
The broadcast
command takes the following form:
broadcast
address
where address is an IP
broadcast or multicast address to which packets are sent.
This command configures a system to act as an
NTP
broadcast server. The address used must be a broadcast or a multicast address. Broadcast address implies the
IPv4
address
255.255.255.255
. By default, routers do not pass broadcast messages. The multicast address can be an
IPv4
Class D address, or an
IPv6
address. The IANA has assigned
IPv4
multicast address
224.0.1.1
and
IPv6
address
FF05::101
(site local) to
NTP
. Administratively scoped
IPv4
multicast addresses can also be used, as described in
RFC 2365 Administratively Scoped IP Multicast.