router advertisement daemon
sends router advertisement packets to
the specified interfaces
. If no interfaces
will still run, but
will not advertise any routes until interfaces are added using
The program will daemonize itself on invocation. It will then send router
advertisement packets periodically, as well as in response to router
solicitation messages sent by end hosts.
Router advertisements can be configured on a per-interface basis, as described
If there is no configuration file entry for an interface, or if the
configuration file does not exist altogether,
sets all the parameters to their
default values. In particular,
all the interface routes from the routing table and advertises them as on-link
also watches the routing table. If an
interface direct route is added on an advertising interface and no static
prefixes are specified by the configuration file,
adds the corresponding prefix to its
Similarly, when an interface direct route is deleted,
will start advertising the prefixes
with zero valid and preferred lifetimes to help the receiving hosts switch to
a new prefix when renumbering. Note, however, that the zero valid lifetime
cannot invalidate the autoconfigured addresses at a receiving host
immediately. According to the specification, the host will retain the address
for a certain period, which will typically be two hours. The zero lifetimes
rather intend to make the address deprecated, indicating that a new
non-deprecated address should be used as the source address of a new
connection. This behavior will last for two hours. Then
will completely remove the prefix
from the advertising list, and succeeding advertisements will not contain the
Moreover, if the status of an advertising interface changes,
will start or stop sending router
advertisements according to the latest status.
option may be used to disable this
will not watch the routing
table and the whole functionality described above will be suppressed.
Basically, hosts MUST NOT send Router Advertisement messages at any time (RFC
4861, Section 6.2.3). However, it would sometimes be useful to allow hosts to
advertise some parameters such as prefix information and link MTU. Thus,
can be invoked if router lifetime is
explicitly set zero on every advertising interface.
The command line options are:
- Specify an alternate location,
configfile, for the configuration file.
By default, /etc/rtadvd.conf is
- Specify an alternate location for the control socket used by
The default is
- Print debugging information.
- Even more debugging information is printed.
- Foreground mode (useful when debugging). Log messages will be dumped to
stderr when this option is specified.
- Specify an interface to join the all-routers site-local multicast group.
rtadvd tries to join the
first advertising interface appearing on the command line. This option has
meaning only with the
-R option, which
enables routing renumbering protocol support.
- Specify an alternative file in which to store the process ID. The default
- Accept router renumbering requests. If you enable it, certain IPsec setup
is suggested for security reasons. This option is currently disabled, and
is ignored by
rtadvd with a warning
- Do not add or delete prefixes dynamically. Only statically configured
prefixes, if any, will be advertised.
to reload the configuration file
. If an invalid parameter
is found in the configuration file upon the reload, the entry will be ignored
and the old configuration will be used. When parameters in an existing entry
will send Router
Advertisement messages with the old configuration but zero router lifetime to
the interface first, and then start to send a new message.
gracefully. In this case,
will transmit router advertisement
with router lifetime 0 to all the interfaces (in accordance with RFC 4861
- The default configuration file.
- The default process ID file.
utility exits 0 on success,
and >0 if an error occurs.
Erik Nordmark, W. A.
Simpson, and Hesham Soliman,
Neighbor Discovery for IP version 6 (IPv6),
Erik Nordmark, and W. A.
Simpson, Neighbor Discovery for IP version 6
(IPv6), RFC 2461 (obsoleted by RFC
Default Router Preferences and More-Specific Routes,
S. Park, L. Beloeil, and
S. Madanapalli, IPv6 Router
Advertisement Options for DNS Configuration, RFC
command first appeared in the WIDE
Hydrangea IPv6 protocol stack kit.
There used to be some text that recommended users not to let
advertise Router Advertisement
messages on an upstream link to avoid undesirable
redirect messages. However, based on the later discussion in the IETF ipng
working group, all routers should rather advertise the messages regardless of
the network topology, in order to ensure reachability.