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RTADVD(8)		     System Manager's Manual		       RTADVD(8)

NAME
     rtadvd -- router advertisement daemon

SYNOPSIS
     rtadvd [-dDfRs] [-c configfile] [-M ifname] [-p pidfile] 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 solic-
     itation 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 config-
     uration  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  adver-
     tising list.

     Similarly, when an interface direct route is deleted, rtadvd will start ad-
     vertising	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
     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 status.

     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 sup-
     pressed.

     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, 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  in-
	     terface  appearing  on  the  command line.  This option has meaning
	     only with the -R option, which enables routing renumbering protocol
	     support.

     -p      Specify an alternative file in which to store the process ID.   The
	     default is /var/run/rtadvd.pid.

     -R      Accept  router  renumbering  requests.   If  you enable it, certain
	     IPsec setup is suggested for security reasons.  This option is cur-
	     rently disabled, and is ignored by rtadvd with a warning message.

     -s      Do not add or delete prefixes dynamically.  Only statically config-
	     ured prefixes, if any, will be advertised.

     Use SIGHUP to reload the configuration file /etc/rtadvd.conf.   If  an  in-
     valid parameter is found in the configuration file upon the reload, the en-
     try  will	be ignored and the old configuration will be used.  When parame-
     ters in an existing entry are updated, rtadvd will send  Router  Advertise-
     ment  messages  with  the old configuration but zero router lifetime to the
     interface first, and then start to send a new message.

     Use SIGTERM to kill rtadvd gracefully.  In this case, rtadvd will	transmit
     router  advertisement  with  router  lifetime  0  to all the interfaces (in
     accordance with RFC 4861 6.2.5).

FILES
     /etc/rtadvd.conf		       The default configuration file.
     /var/run/rtadvd.pid	       The default process ID file.

EXIT STATUS
     The rtadvd utility exits 0 on success, and >0 if an error occurs.

SEE ALSO
     rtadvd.conf(5), rtsol(8)

     Thomas Narten, Erik Nordmark, W. A. Simpson, and Hesham  Soliman,	Neighbor
     Discovery for IP version 6 (IPv6), RFC 4861.

     Thomas  Narten, Erik Nordmark, and W. A. Simpson, Neighbor Discovery for IP
     version 6 (IPv6), RFC 2461 (obsoleted by RFC 4861).

     Richard Draves, Default Router Preferences and More-Specific Routes, draft-
     ietf-ipngwg-router-selection-xx.txt.

     J. Jeong, S. Park, L. Beloeil, and S. Madanapalli, IPv6  Router  Advertise-
     ment Options for DNS Configuration, RFC 6106.

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 adver-
     tise Router Advertisement messages on an upstream link to avoid undesirable
     icmp6(4) 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.

FreeBSD 8.3			  July 14, 2011 		       RTADVD(8)
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