215 lines
6.7 KiB
Groff
215 lines
6.7 KiB
Groff
.\" $NetBSD: rtadvd.8,v 1.29 2020/04/21 12:19:44 wiz Exp $
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.\" $KAME: rtadvd.8,v 1.24 2002/05/31 16:16:08 jinmei Exp $
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.\"
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.\" Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the project nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd April 21, 2020
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.Dt RTADVD 8
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.Os
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.Sh NAME
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.Nm rtadvd
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.Nd router advertisement daemon
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.Sh SYNOPSIS
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.Nm
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.Op Fl CDdfs
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.Op Fl c Ar configfile
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.Op Fl p Ar pidfile
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.Ar interface ...
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.Sh DESCRIPTION
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.Nm
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sends router advertisement packets to the specified interfaces.
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.Pp
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The program will daemonize itself on invocation.
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It will then send router advertisement packets periodically, as well
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as in response to router solicitation messages sent by end hosts.
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.Pp
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Router advertisements can be configured on a per-interface basis, as
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described in
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.Xr rtadvd.conf 5 .
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.Pp
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If there is no configuration file entry for an interface,
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or if the configuration file does not exist at all,
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.Nm
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sets all the parameters to their default values.
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In particular,
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.Nm
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reads all the interface routes from the routing table and advertises
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them as on-link prefixes.
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.Pp
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.Nm
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also watches the routing table.
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If an interface direct route is
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added on an advertising interface and no static prefixes are
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specified by the configuration file,
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.Nm
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adds the corresponding prefix to its advertising list.
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.Pp
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Similarly, when an interface direct route is deleted,
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.Nm
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will start advertising the prefixes with zero valid and preferred
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lifetimes to help the receiving hosts switch to a new prefix when
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renumbering.
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Note, however, that the zero valid lifetime cannot invalidate the
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autoconfigured addresses at a receiving host immediately.
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According to the specification, the host will retain the address
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for a certain period, which will typically be two hours.
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The zero lifetimes rather intend to make the address deprecated,
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indicating that a new non-deprecated address should be used as the
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source address of a new connection.
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This behavior will last for two hours.
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Then
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.Nm
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will completely remove the prefix from the advertising list,
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and succeeding advertisements will not contain the prefix information.
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.Pp
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Moreover, if the status of an advertising interface changes,
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.Nm
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will start or stop sending router advertisements according
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to the latest status.
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.Pp
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The
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.Fl s
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option may be used to disable this behavior;
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.Nm
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will not watch the routing table and the whole functionality described
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above will be suppressed.
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.Pp
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Basically, hosts MUST NOT send Router Advertisement messages at any
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time (RFC 2461, Section 6.2.3).
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However, it would sometimes be useful to allow hosts to advertise some
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parameters such as prefix information and link MTU.
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Thus,
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.Nm
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can be invoked if router lifetime is explicitly set to zero on every
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advertising interface.
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.Pp
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The command line options are:
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.Bl -tag -width indent
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.\"
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.It Fl C
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Don't expire the existing configuration on receipt of SIGHUP.
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This option is only intended to aid the testing of clients that consume
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Router Advertisement messages.
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.It Fl c Ar configfile
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Specify an alternate location,
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.Ar configfile ,
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for the configuration file.
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By default,
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.Pa /etc/rtadvd.conf
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is used.
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.It Fl D
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Instead of printing errors using
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.Xr syslog 3
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send them to
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.Dv stderr .
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Also when
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.Xr poll 2
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fails, exit instead of retrying.
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.It Fl d
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Print debugging information.
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Repeating this option, adds more verbose debugging.
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.It Fl f
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Foreground mode (useful when debugging).
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Log messages will be dumped to stderr when this option is specified.
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.\".It Fl m
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.\"Enables mobile IPv6 support.
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.\"This changes the content of router advertisement option, as well as
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.\"permitted configuration directives.
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.It Fl p Ar pidfile
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Specify an alternate location,
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.Ar pidfile ,
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for the PID file.
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By default,
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.Pa /var/run/rtadvd.pid
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is used.
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.It Fl s
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Do not add or delete prefixes dynamically.
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Only statically configured prefixes, if any, will be advertised.
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.El
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.Pp
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Use
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.Dv SIGHUP
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to reload the configuration file
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.Pa /etc/rtadvd.conf .
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If an invalid parameter is found in the configuration file upon the reload, the
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entry will be ignored and the old configuration will be used.
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When parameters in an existing entry are updated and the
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.Fl C
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flag is not used,
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.Nm
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will send Router Advertisement messages with the old configuration but zero
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router lifetime to the interface first, and then start to send a new message.
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.Pp
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Upon receipt of signal
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.Dv SIGUSR1 ,
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.Nm
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will dump the current internal state into
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.Pa /var/run/rtadvd.dump .
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.Pp
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Use
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.Dv SIGTERM
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to kill
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.Nm
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gracefully.
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In this case,
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.Nm
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will transmit router advertisement with router lifetime 0
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to all the interfaces
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.Pq in accordance with RFC 2461 6.2.5 .
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.Sh FILES
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.Bl -tag -width /var/run/rtadvd.dumpXX -compact
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.It Pa /etc/rtadvd.conf
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The default configuration file.
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.It Pa /var/run/rtadvd.pid
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Contains the PID of the currently running
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.Nm .
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.It Pa /var/run/rtadvd.dump
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The file in which
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.Nm
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dumps its internal state.
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.El
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.Sh EXIT STATUS
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.Ex -std rtadvd
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.Sh SEE ALSO
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.Xr rtadvd.conf 5 ,
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.Xr rtsol 8
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.Sh HISTORY
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The
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.Nm
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command first appeared in the WIDE Hydrangea IPv6 protocol stack kit.
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.Sh BUGS
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There used to be some text that recommended users not to let
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.Nm
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advertise Router Advertisement messages on an upstream link to avoid
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undesirable
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.Xr icmp6 4
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redirect messages.
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However, based on later discussion in the IETF IPng working group,
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all routers should rather advertise the messages regardless of
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the network topology, in order to ensure reachability.
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