Finding out what application is running on a specific port in Windows XP is easy by using two command line utilities. By using netstat with the proper switches you can list out all of the ports that are being used and then use Tasklist to list all of the applications that are running. The combination of the two utilities will allow you to figure out which application us using which port. As an example you can use the below directions to figure out what application is using port 80 for instance.
- Open Command Prompt: Click Start in the lower left hand corner of your PC and then select Run from the pop up. Type command in the Run window and click Enter to open up the command prompt.