44ripd.8

.Dd January 28, 2017
.Dt 44RIPD 8
.Os
.Sh NAME
.Nm 44ripd
.Nd AMPR route update daemon
.Sh SYNOPSIS
.Nm
.Op Fl d
.Op Fl T Ar routetable
.Op Fl L Ar localip
.Op Fl I Ar ignoreroute
.Op Fl s Ar ifnum
.Sh DESCRIPTION
The
.Nm
daemon handles route and tunnel maintenance for the AMPR
amateur radio network (IPv4 44/8: http://www.ampr.org)
using a modified version of the RIPv2 protocol (RFC 2453).

The AMPR network is a mesh wherin each site sets up an
IPENCAP tunnel to (almost) every other site. (As of 2017
there are 594 disparate AMPR networks).

The daemon listens on a multicast socket for UDP datagrams
directed to the RIP port. It discards packets that are not
valid, authenticated RIP packets (though authentication is
simply string comparison against a plaintext password: it is
not particularly strong and could be trivially broken). It
maintains an internal copy of the AMPRNet routing table as
well as a set of active tunnels.

After processing a RIP packet, the daemon walks through the
routing table, looking for routes to expire. If a route
expires it is noted for removal from the table. Expiration
time is much greater than the expected interval between
RIP broadcasts.

Routes keep a reference to a tunnel. When a route is added
that refers to an non-existent tunnel, the tunnel is created
and set up. If a route referring to a tunnel is removed or
changed to a different tunnel, the tunnel's reference count
is decremented. If a tunnel's reference count drops to zero,
it is torn down and removed.

Each tunnel corresponds to a virtual IP encapsulation
interface; see gif(4) for details.  The daemon dynamically
creates and destroys these interfaces as required.  A bitmap
of active interfaces is kept and the lowest unused interface
number is always allocated when a new tunnel is created.
.Sh SEE ALSO
.Xr ifconfig 8 ,
.Xr route 8
.Sh AUTHORS
.An "Dan Cross"