You ever have a problem trying to start an application and it failed to start because the network port was occupied by another application? To find out the application that using the port is painstaking. The following commands could help you.
In the following example, I am trying to find what is the process that is occupying the port 8080.
Windows
C:\Documents and Settings\terence>netstat -aon | findstr 8080
TCP 0.0.0.0:8080 0.0.0.0:0 LISTENING 1748C:\Documents and Settings\terence>tasklist | findstr 1748
TNSLSNR.EXE 1748 Console 0 6,264 K
Linux
[root@mail03a ~]# netstat -nap | grep 8080 | grep LISTEN
tcp 0 0 0.0.0.0:8080 0.0.0.0:* LISTEN 2685/openvpn