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RTADVD(8)		  BSD 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.  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 ad-
     vertising 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 ad-
     dress 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 pre-
     fix information.

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

     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

     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-
	     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-

     -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).

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

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

     rtadvd.conf(5), rtsol(8)

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

     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

BSD				 May 17, 1998				   BSD


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