The answer is technically /bin/ps -ef. But what you really want is /bin/netstat -plunt. Netstat prints network connections, routing tables, interface statistics, masquerade connections, and multicast memberships. The switches that make this possible and handy are:
-p = Show the PID and program name associated with the open ports -l = Show only the ports that are listening (open) -u = Provide answers for udp addresses -n = Skip turning numers into names (primarly dns looksups; this is often VERY helpful when troubleshooting) -t = Answer for tcp addresses
You do know /bin/netstat -rn, right? It show the routing tables. Of course, if you're interested in drinking from the firehose, there's /bin/netstat -an.