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.\"	$FreeBSD$
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.Dd May 17, 1998
.Dt RTADVD 8
.Os
.Sh NAME
.Nm rtadvd
.Nd router advertisement daemon
.Sh SYNOPSIS
.Nm
.Op Fl c Ar configfile
.Op Fl dDfmRs
.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 and no static prefixes are
specified by the configuration file,
.Nm
adds/deletes the corresponding prefix to/from its advertising list,
respectively.
The
.Ic Fl s
may be used to disable this behavior.
Moreover, if the status of an advertising interface changes,
.Nm
will start or stop sending router advertisements according
to the latest status.
.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 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.
.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.
.It Pa /var/run/rtadvd.pid
contains pid of the currently running
.Nm rtadvd .
.It Pa /var/run/rtadvd.dump
on which
.Nm
dumps its internal state.
.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.