ifdepd implements dependencies between network interfaces in a
reliable way. If any of the source interfaces fails, ifdepd sets all
destination interfaces to state down. If all source interfaces are active,
ifdepd sets all destination interfaces to state up.

For example, it can be used with carp(4) to provide failover functionality
on gateways/firewalls.

ifdepd is a simple replacement for ifstated and was written because of problems
with ifstated.

Alexander Hausner <alex@hugo.bmg.gv.at>