Bill Sommerfeld <sommerfeld@orchard.medford.ma.us> writes:

>> An idea which has occurred to me was to add a new signal,
>> SIGIFCH, analogous to SIGWINCH, which is delivered to user
>> processes expressing interest in it when the "local address set" of a
>> system changes.

Instead of adding a new signal, you could do something akin to (or
using) the routing socket.

		Marc