Identify processes running on a network port

If you want to check what process is using one of your network ports a good utility to use is netstat:

[root@sideshow ~]# netstat -natup | grep 161
udp 0 0 0.0.0.0:161 0.0.0.0:* 9580/snmpd

In this example I checked port 161 and found that snmpd (a network monitoring program) was running on the port.  You could also grep for "apache" to see what ports apache is listening on.