.\"	$OpenBSD: dvmrpd.8,v 1.12 2023/03/02 17:09:53 jmc Exp $
.\"
.\" Copyright (c) 2004, 2005, 2006 Esben Norby <norby@openbsd.org>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.Dd $Mdocdate: March 2 2023 $
.Dt DVMRPD 8
.Os
.Sh NAME
.Nm dvmrpd
.Nd Distance Vector Multicast Routing Protocol (DVMRP) daemon
.Sh SYNOPSIS
.Nm
.Op Fl dnv
.Op Fl f Ar file
.Sh DESCRIPTION
.Nm
is the Distance Vector Multicast Routing Protocol
.Pq DVMRP
daemon, which manages multicast routing tables.
This implementation supports DVMRP version 3.255,
thus it is only capable of maintaining IPv4 multicast routing tables.
.Pp
DVMRP uses a distance vector routing algorithm to build
reverse path multicast delivery trees.
A flood and prune approach is used to determine which branches in
the network have multicast listeners.
The usual drawbacks of a distance vector route protocol applies to DVMRP:
slow convergence and scalability issues.
.Pp
DVMRP routers communicate via the multicast group 224.0.0.4
All DVMRP Routers.
IP protocol number 2
.Pq IGMP
is used, furthermore DVMRP packets omit the use of TCP and UDP.
.Pp
It is possible to interconnect multicast networks with the use of tunnels.
Tunnels can traverse routers and networks not supporting multicast.
.Nm
does not support tunneling as described in RFC 1075,
since it has been abandoned.
.Nm
can tunnel multicast traffic using generic solutions such as
.Xr gre 4 .
.Pp
DVMRP is used for handling multicast routing exclusively.
It is not required that a unicast routing protocol is used in
conjunction with DVMRP.
.Pp
To have
.Nm
enabled at boot time, use
.Dq rcctl enable dvmrpd ,
which sets
.Pp
.Dl dvmrpd_flags=\(dq\(dq
.Pp
in
.Xr rc.conf.local 8 .
.Pp
A running
.Nm
can be controlled with the
.Xr dvmrpctl 8
utility.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl d
Do not daemonize.
If this option is specified,
.Nm
will run in the foreground and log to
.Em stderr .
.It Fl f Ar file
Specify an alternative configuration file.
.It Fl n
Configtest mode.
Only check the configuration file for validity.
.It Fl v
Produce more verbose output.
.El
.Sh FILES
.Bl -tag -width "/var/run/dvmrpd.sockXX" -compact
.It Pa /etc/dvmrpd.conf
Default
.Nm
configuration file.
.It Pa /var/run/dvmrpd.sock
.Ux Ns -domain
socket used for communication with
.Xr dvmrpctl 8 .
.El
.Sh SEE ALSO
.Xr dvmrpd.conf 5 ,
.Xr dvmrpctl 8
.Sh STANDARDS
.Rs
.%D August 2000
.%R draft-ietf-idmr-dvmrp-v3-11
.%T DVMRP Version 3
.Re
.Sh HISTORY
The
.Nm
program first appeared in
.Ox 4.0 .