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rtadvd(8)

NAME

     rtadvd -- router advertisement daemon

SYNOPSIS

     rtadvd [-dDfMRs] [-c configfile] interface ...

DESCRIPTION

     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
     described 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.  If an interface direct route is
     added on an advertising interface and no static prefixes are specified by
     the configuration file, rtadvd adds the corresponding prefix to its
     advertising list.

     Similarly, when an interface direct route is deleted, rtadvd will start
     advertising the prefixes with zero valid and preferred lifetimes to help
     the receiving hosts switch to a new prefix when renumbering.  Note, how-
     ever, that the zero valid lifetime cannot invalidate the autoconfigured
     addresses at a receiving host immediately.  According to the specifica-
     tion, 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 rtadvd will completely remove the prefix from
     the advertising list, and succeeding advertisements will not contain the
     prefix information.

     Moreover, if the status of an advertising interface changes, rtadvd will
     start or stop sending router advertisements according to the latest sta-
     tus.

     The -s option may be used to disable this behavior; rtadvd 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 2461, 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, 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.

     -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-
	     col support.

     -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-
	     sage.

     -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 RFC2461 6.2.5).

RETURN VALUES

     The rtadvd program exits 0 on success, and >0 on failures.

FILES

     /etc/rtadvd.conf		       The default configuration file.
     /var/run/rtadvd.pid	       contains the pid of the currently run-
				       ning rtadvd.
     /var/run/rtadvd.dump	       The file in which rtadvd dumps its
				       internal state.

SEE ALSO

     rtadvd.conf(5), rtsol(8)

HISTORY

     The rtadvd command first appeared in the WIDE Hydrangea IPv6 protocol
     stack kit.

BUGS

     There used to be some text that recommended users not to let rtadvd
     advertise Router Advertisement messages on an upstream link to avoid
     undesirable icmp6(4) redirect messages.  However, based on the later dis-
     cussion in the IETF ipng working group, all routers should rather adver-
     tise the messages regardless of the network topology, in order to ensure
     reachability.

FreeBSD 5.4			 May 17, 1998			   FreeBSD 5.4

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