.\" $FreeBSD: src/usr.sbin/rtadvd/rtadvd.8,v 126.96.36.199 2001/08/16 15:56:30 ru Exp $ .\" $KAME: rtadvd.8,v 1.24 2002/05/31 16:16:08 jinmei Exp $ .\" .\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. Neither the name of the project nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .Dd August 27, 2011 .Dt RTADVD 8 .Os .Sh NAME .Nm rtadvd .Nd router advertisement daemon .Sh SYNOPSIS .Nm .Op Fl dDfMRs .Op Fl c Ar configfile .Op Fl F Ar dumpfile .Op Fl p Ar pidfile .Ar interface ... .Sh DESCRIPTION .Nm sends router advertisement packets to the specified .Ar interfaces . .Pp 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. .Pp Router advertisements can be configured on a per-interface basis, as described in .Xr rtadvd.conf 5 . .Pp If there is no configuration file entry for an interface, or if the configuration file does not exist altogether, .Nm sets all the parameters to their default values. In particular, .Nm reads all the interface routes from the routing table and advertises them as on-link prefixes. .Pp .Nm 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, .Nm adds the corresponding prefix to its advertising list. .Pp Similarly, when an interface direct route is deleted, .Nm 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 .Nm will completely remove the prefix from the advertising list, and succeeding advertisements will not contain the prefix information. .Pp Moreover, if the status of an advertising interface changes, .Nm will start or stop sending router advertisements according to the latest status. .Pp The .Fl s option may be used to disable this behavior; .Nm will not watch the routing table and the whole functionality described above will be suppressed. .Pp 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, .Nm can be invoked if router lifetime is explicitly set zero on every advertising interface. .Pp The command line options are: .Bl -tag -width indent .\" .It Fl c Specify an alternate location, .Ar configfile , for the configuration file. By default, .Pa /etc/rtadvd.conf is used. .It Fl d Print debugging information. .It Fl D Even more debugging information is printed. .It Fl f Foreground mode (useful when debugging). Log messages will be dumped to stderr when this option is specified. .It Fl F Specify an alternative file in which to dump internal states when .Nm receives signal .Dv SIGUSR1 . The default is .Pa /var/run/rtadvd.dump . .It Fl M Specify an interface to join the all-routers site-local multicast group. By default, .Nm tries to join the first advertising interface appearing on the command line. This option has meaning only with the .Fl R option, which enables routing renumbering protocol support. .It Fl p Specify an alternative file in which to store the process ID. The default is .Pa /var/run/rtadvd.pid. .It Fl 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 .Nm with a warning message. .It Fl s Do not add or delete prefixes dynamically. Only statically configured prefixes, if any, will be advertised. .El .Pp Upon receipt of signal .Dv SIGUSR1 , .Nm will dump the current internal state into .Pa /var/run/rtadvd.dump or the file specified with option .Fl F . .Pp Use .Dv SIGTERM to kill .Nm gracefully. In this case, .Nm will transmit router advertisement with router lifetime 0 to all the interfaces .Pq in accordance with RFC2461 6.2.5 . .Sh FILES .Bl -tag -width Pa -compact .It Pa /etc/rtadvd.conf The default configuration file. .It Pa /var/run/rtadvd.pid The default process ID file. .It Pa /var/run/rtadvd.dump The default file in which .Nm dumps its internal state. .El .Sh EXIT STATUS .Ex -std .Sh SEE ALSO .Xr rtadvd.conf 5 , .Xr rtsol 8 .Sh HISTORY The .Nm command first appeared in the WIDE Hydrangea IPv6 protocol stack kit. .Sh BUGS There used to be some text that recommended users not to let .Nm advertise Router Advertisement messages on an upstream link to avoid undesirable .Xr 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.