1.\" $NetBSD: rtadvd.8,v 1.29 2020/04/21 12:19:44 wiz Exp $ 2.\" $KAME: rtadvd.8,v 1.24 2002/05/31 16:16:08 jinmei Exp $ 3.\" 4.\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project. 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the project nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.Dd April 21, 2020 32.Dt RTADVD 8 33.Os 34.Sh NAME 35.Nm rtadvd 36.Nd router advertisement daemon 37.Sh SYNOPSIS 38.Nm 39.Op Fl CDdfs 40.Op Fl c Ar configfile 41.Op Fl p Ar pidfile 42.Ar interface ... 43.Sh DESCRIPTION 44.Nm 45sends router advertisement packets to the specified interfaces. 46.Pp 47The program will daemonize itself on invocation. 48It will then send router advertisement packets periodically, as well 49as in response to router solicitation messages sent by end hosts. 50.Pp 51Router advertisements can be configured on a per-interface basis, as 52described in 53.Xr rtadvd.conf 5 . 54.Pp 55If there is no configuration file entry for an interface, 56or if the configuration file does not exist at all, 57.Nm 58sets all the parameters to their default values. 59In particular, 60.Nm 61reads all the interface routes from the routing table and advertises 62them as on-link prefixes. 63.Pp 64.Nm 65also watches the routing table. 66If an interface direct route is 67added on an advertising interface and no static prefixes are 68specified by the configuration file, 69.Nm 70adds the corresponding prefix to its advertising list. 71.Pp 72Similarly, when an interface direct route is deleted, 73.Nm 74will start advertising the prefixes with zero valid and preferred 75lifetimes to help the receiving hosts switch to a new prefix when 76renumbering. 77Note, however, that the zero valid lifetime cannot invalidate the 78autoconfigured addresses at a receiving host immediately. 79According to the specification, the host will retain the address 80for a certain period, which will typically be two hours. 81The zero lifetimes rather intend to make the address deprecated, 82indicating that a new non-deprecated address should be used as the 83source address of a new connection. 84This behavior will last for two hours. 85Then 86.Nm 87will completely remove the prefix from the advertising list, 88and succeeding advertisements will not contain the prefix information. 89.Pp 90Moreover, if the status of an advertising interface changes, 91.Nm 92will start or stop sending router advertisements according 93to the latest status. 94.Pp 95The 96.Fl s 97option may be used to disable this behavior; 98.Nm 99will not watch the routing table and the whole functionality described 100above will be suppressed. 101.Pp 102Basically, hosts MUST NOT send Router Advertisement messages at any 103time (RFC 2461, Section 6.2.3). 104However, it would sometimes be useful to allow hosts to advertise some 105parameters such as prefix information and link MTU. 106Thus, 107.Nm 108can be invoked if router lifetime is explicitly set to zero on every 109advertising interface. 110.Pp 111The command line options are: 112.Bl -tag -width indent 113.\" 114.It Fl C 115Don't expire the existing configuration on receipt of SIGHUP. 116This option is only intended to aid the testing of clients that consume 117Router Advertisement messages. 118.It Fl c Ar configfile 119Specify an alternate location, 120.Ar configfile , 121for the configuration file. 122By default, 123.Pa /etc/rtadvd.conf 124is used. 125.It Fl D 126Instead of printing errors using 127.Xr syslog 3 128send them to 129.Dv stderr . 130Also when 131.Xr poll 2 132fails, exit instead of retrying. 133.It Fl d 134Print debugging information. 135Repeating this option, adds more verbose debugging. 136.It Fl f 137Foreground mode (useful when debugging). 138Log messages will be dumped to stderr when this option is specified. 139.\".It Fl m 140.\"Enables mobile IPv6 support. 141.\"This changes the content of router advertisement option, as well as 142.\"permitted configuration directives. 143.It Fl p Ar pidfile 144Specify an alternate location, 145.Ar pidfile , 146for the PID file. 147By default, 148.Pa /var/run/rtadvd.pid 149is used. 150.It Fl s 151Do not add or delete prefixes dynamically. 152Only statically configured prefixes, if any, will be advertised. 153.El 154.Pp 155Use 156.Dv SIGHUP 157to reload the configuration file 158.Pa /etc/rtadvd.conf . 159If an invalid parameter is found in the configuration file upon the reload, the 160entry will be ignored and the old configuration will be used. 161When parameters in an existing entry are updated and the 162.Fl C 163flag is not used, 164.Nm 165will send Router Advertisement messages with the old configuration but zero 166router lifetime to the interface first, and then start to send a new message. 167.Pp 168Upon receipt of signal 169.Dv SIGUSR1 , 170.Nm 171will dump the current internal state into 172.Pa /var/run/rtadvd.dump . 173.Pp 174Use 175.Dv SIGTERM 176to kill 177.Nm 178gracefully. 179In this case, 180.Nm 181will transmit router advertisement with router lifetime 0 182to all the interfaces 183.Pq in accordance with RFC 2461 6.2.5 . 184.Sh FILES 185.Bl -tag -width /var/run/rtadvd.dumpXX -compact 186.It Pa /etc/rtadvd.conf 187The default configuration file. 188.It Pa /var/run/rtadvd.pid 189Contains the PID of the currently running 190.Nm . 191.It Pa /var/run/rtadvd.dump 192The file in which 193.Nm 194dumps its internal state. 195.El 196.Sh EXIT STATUS 197.Ex -std rtadvd 198.Sh SEE ALSO 199.Xr rtadvd.conf 5 , 200.Xr rtsol 8 201.Sh HISTORY 202The 203.Nm 204command first appeared in the WIDE Hydrangea IPv6 protocol stack kit. 205.Sh BUGS 206There used to be some text that recommended users not to let 207.Nm 208advertise Router Advertisement messages on an upstream link to avoid 209undesirable 210.Xr icmp6 4 211redirect messages. 212However, based on later discussion in the IETF IPng working group, 213all routers should rather advertise the messages regardless of 214the network topology, in order to ensure reachability. 215