.\"	$OpenBSD: rtadvd.8,v 1.9 2000/03/19 17:57:14 aaron Exp $
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.\"     KAME Id: rtadvd.8,v 1.5 2000/02/08 05:19:36 itojun Exp
.\"
.Dd May 17, 1998
.Dt RTADVD 8
.Os
.Sh NAME
.Nm rtadvd
.Nd router advertisement daemon
.Sh SYNOPSIS
.Nm rtadvd
.Op Fl c Ar configfile
.Op Fl dDfRs
.Ar interface ...
.Sh DESCRIPTION
.Nm
advertises router advertisement packet to the specified
.Ar interfaces .
.Pp
The program will daemonize itself on invocation.
It will then periodically send router advertisement packets, 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
In the event of 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.
By default, if an interface direct route is
added/deleted on an advertising interface,
.Nm
adds/deletes the corresponding prefix to/from its advertising list,
respectively.
The
.Ic Fl s
command line option may be used to disable this behavior.
.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).
.\".It Fl m
.\"Enables mobile IPv6 support.
.\"This changes the content of router advertisement option, as well as
.\"permitted configuration directives.
.It Fl R
Accept router renumbering requests.
If you enable it, certain IPsec setup is suggested for security reasons.
.It Fl s
Do not monitor routing table changes (static prefix).
.El
.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 according to RFC2461 6.2.5 .
.Sh RETURN VALUES
The program exits with 0 on success, and non-zero on failures.
.Sh FILES
.Bl -tag -width /etc/rtadvd.conf -compact
.It Pa /etc/rtadvd.conf
The default configuration file.
.El
.Sh SEE ALSO
.Xr daemon 3 ,
.Xr rtadvd.conf 5 ,
.Xr rtsol 8
.Sh HISTORY
The
.Nm
command first appeared in WIDE Hydrangea IPv6 protocol stack kit.
.Sh CAVEAT
Router advertisements should only be performed downstream.
Erroneous upstream advertisements will cause
.Xr icmp6 4
redirect packet storms in the subnet, as (per the specification) the
advertising router is assumed to become the default router for
end hosts in the subnet.