RTADVD(8) OpenBSD System Manager's Manual RTADVD(8)
rtadvd - router advertisement daemon
rtadvd [-dDfMRs] [-c configfile] interface ...
rtadvd sends router advertisement packets to the specified interfaces.
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 de-
scribed in rtadvd.conf(5).
If there is no configuration file entry for an interface, or if the con-
figuration file does not exist altogether, rtadvd sets all the parameters
to their default values. In particular, rtadvd reads all the interface
routes from the routing table and advertises them as on-link prefixes.
rtadvd also watches the routing table. By default, if an interface di-
rect route is added/deleted on an advertising interface and no static
prefixes are specified by the configuration file, rtadvd adds/deletes the
corresponding prefix to/from its advertising list, respectively. The -s
option may be used to disable this behavior. Moreover, if the status of
an advertising interface changes, rtadvd will start or stop sending
router advertisements according to the latest status.
Basically, hosts MUST NOT send Router Advertisement messages at any time
(RFC 2461, Section 6.2.3). However, it would sometimes be useful to al-
low hosts to advertise some parameters such as prefix information and
link MTU. Thus, rtadvd can be invoked if router lifetime is explicitly
set zero on every advertising interface.
The command line options are:
-c Specify an alternate location, configfile, for the configuration
file. By default, /etc/rtadvd.conf is used.
-d Print debugging information.
-D Even more debugging information is printed.
-f Foreground mode (useful when debugging). Log messages will be
dumped to stderr when this option is specified.
-M Specify an interface to join the all-routers site-local multicast
group. By default, 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 proto-
-R 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 mes-
-s Do not add or delete prefixes dynamically. Only statically con-
figured prefixes, if any, will be advertised.
Upon receipt of signal SIGUSR1, rtadvd will dump the current internal
state into /var/run/rtadvd.dump.
Use SIGTERM to kill rtadvd gracefully. In this case, rtadvd will trans-
mit router advertisement with router lifetime 0 to all the interfaces (in
accordance with RFC 2461 6.2.5).
The rtadvd program exits 0 on success, and >0 on failures.
/etc/rtadvd.conf The default configuration file.
/var/run/rtadvd.pid contains the pid of the currently run-
/var/run/rtadvd.dump The file in which rtadvd dumps its in-
The rtadvd command first appeared in the WIDE Hydrangea IPv6 protocol
There used to be some text that recommended users not to let rtadvd ad-
vertise Router Advertisement messages on an upstream link to avoid unde-
sirable icmp6(4) redirect messages. However, based on the later discus-
sion in the IETF IPng working group, all routers should rather advertise
the messages regardless of the network topology, in order to ensure
OpenBSD 3.6 May 17, 1998 2