How to find which process is listeing on a given port?

[Paul Goyette <paul%whooppee.com@localhost>]

I vaguely recall that there was a way to figure this out, but I can't 
for the life of me remember!

I've got a _lot_ of traffic hitting my system on UDP 51413, and a 
netstat shows that the machine is listening on this port for both UDP 
and TCP.  netstat -A gives me the pcb address for the active sessions 
(but, apparently, not for the listener), but I can't remember how to 
figure out which process has that pcb/file open.


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