Network – How to find out what is listening or using a port

I was trying to install software but it failed because the install stated that port 80 was in use. It didn’t say what was using it. I needed to find out so I could shut the application down in order to install my software. Come to find out, both skype and IIS were using the port.

In order to determine what was using the port, I brought up a command box and typed the following:

netstat -aon | findstr 0.0:80

-a = Display all connections and listening ports.
-n = Displays addresses and port numbers in numerical form.
-0 = Displays the owning process ID associated with each connection. (This is used  to locate the PID column in the processes tab of the task manager to find the process.
findstr = States I am only interested in port 80

The results?

TCP 0.0.0.0:80    0.0.0.0:0    LISTENING 3328

3328 is the PID. I then open the task manager, went to the processes tab, searched for PID = 3328 and stopped the process.

I then proceeded to successfully install my software.