.\"	$OpenBSD: rtsold.8,v 1.16 2003/06/12 12:59:53 jmc Exp $
.\"	$KAME: rtsold.8,v 1.17 2001/07/09 22:30:37 itojun Exp $
.\"
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.Dd May 17, 1998
.Dt RTSOLD 8
.Os
.\"
.Sh NAME
.Nm rtsold
.Nd router solicitation daemon
.\"
.Sh SYNOPSIS
.Nm rtsold
.Op Fl dDfm1
.Ar interface ...
.Nm rtsold
.Op Fl dDfm1
.Fl a
.Nm rtsol
.Op Fl dD
.Ar interface ...
.Nm rtsol
.Op Fl dD
.Fl a
.\"
.Sh DESCRIPTION
.Nm
is the daemon program to send ICMPv6 Router Solicitation messages
on the specified interfaces.
If a node (re)attaches to a link,
.Nm
sends some Router Solicitations on the link destined to the link-local scope
all-routers multicast address to discover new routers
and to get non link-local addresses.
.Pp
.Nm
should be used on IPv6 hosts
.Pq non-router nodes
only.
.Pp
If you invoke the program as
.Nm rtsol ,
it will transmit probes from the specified
.Ar interface ,
without becoming a daemon.
In other words,
.Nm rtsol
behaves as
.Do
.Nm
.Fl f1
.Ar interfaces
.Dc .
.Pp
Specifically,
.Nm
sends at most 3 Router Solicitations on an interface
after one of the following events:
.Pp
.Bl -bullet -compact
.It
Just after invocation of
.Nm
daemon.
.It
The interface is up after a temporary interface failure.
.Nm
detects such failures by periodically probing to see if the status
of the interface is active or not.
Note that some network cards and drivers do not allow the extraction
of link state.
In such cases,
.Nm
cannot detect the change of the interface status.
.It
Every 60 seconds if the
.Fl m
option is specified and the
.Nm
daemon cannot get the interface status.
This feature does not conform to the IPv6 neighbor discovery
specification, but is provided for mobile stations.
The default interval for router advertisements, which is on the order of 10
minutes, is slightly long for mobile stations.
This feature is provided
for such stations so that they can find new routers as soon as possible
when they attach to another link.
.El
.Lp
Once
.Nm
has sent a Router Solicitation, and has received a valid Router Advertisement,
it refrains from sending additional solicitations on that interface, until
the next time one of the above events occurs.
.Lp
When sending a Router Solicitation on an interface,
.Nm
includes a Source Link-layer address option if the interface
has a link-layer address.
.Pp
Upon receipt of signal
.Dv SIGUSR1 ,
.Nm
will dump the current internal state into
.Pa /var/run/rtsold.dump .
.\"
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl a
Autoprobe outgoing interface.
.Nm
will try to find a non-loopback, non-point-to-point, IPv6-capable interface.
If
.Nm
finds multiple interfaces,
.Nm
will exit with error.
.\"
.It Fl d
Enable debugging.
.It Fl D
Enable more debugging including the printing of internal timer information.
.It Fl f
.Fl f
prevents
.Nm
from becoming a daemon (foreground mode).
Warning messages are generated to standard error
instead of
.Xr syslog 3 .
.It Fl m
Enable mobility support.
If this option is specified,
.Nm
sends probing packets to default routers that have advertised Router
Advertisements
when the node (re)attaches to an interface.
Moreover, if the option is specified,
.Nm
periodically sends Router Solicitation on an interface that does not support
.Dv SIOCGIFMEDIA
ioctl.
.It Fl 1
Perform only one probe.
Transmit Router Solicitation packets until at least one valid Router
Advertisement packet has arrived on each
.Ar interface ,
then exit.
.El
.Sh RETURN VALUES
The
.Nm
program exits 0 on success, and >0 on failures.
.\"
.Sh FILES
.Bl -tag -width /var/run/rtsold.dump -compact
.It Pa /var/run/rtsold.pid
the pid of the currently running
.Nm rtsold .
.It Pa /var/run/rtsold.dump
dumps internal state on.
.El
.\"
.Sh SEE ALSO
.Xr rtadvd 8 ,
.Xr sysctl 8
.\"
.Sh HISTORY
The
.Nm
command is based on the
.Nm rtsol
command, which first appeared in WIDE/KAME IPv6 protocol stack kit.
.Nm rtsol
is now integrated into
.Nm rtsold .
.\"
.Sh BUGS
In some operating systems, when a PCMCIA network card is removed
and reinserted, the corresponding interface index is changed.
However,
.Nm
assumes such changes will not occur, and always uses the index that
it got at invocation.
As a result,
.Nm
may not work if you reinsert a network card.
In such a case,
.Nm
should be killed and restarted.
.Pp
The IPv6 autoconfiguration specification assumes a single-interface host.
You may see kernel error messages if you try to autoconfigure a host with
multiple interfaces.
Also, it seems contradictory for
.Nm
to accept multiple
.Ar interface
arguments.