Let’s say that we are looking for port 80 — IIS, Apache and other web servers listen in port 80, so when you are having problems starting Apache, this technique will be useful. Here is the command.
-a means list all active connections and their ports. -o means include their process IDs. -n means display the port numbers numerically.
The pipe symbol ( | ) means, that instead of the result of netstat being displayed on the screen, feed it’s result to the findstr process — we are looking specifically for the line which has 0.0:80 — you actually don’t need findstr, but I don’t want to scroll down and hunt down manually which app is using port 80. You might see something like this.
Aha! now we know that process 560 is using port 80 (that last column right there, is the process ID), you could press CTRL-ALT-DEL now to show the process window, and manually look up which app has the process ID 560, or you could enter ..
tasklist is another Windows command line utility which shows you a list of all active processes, again I’d feed it to the findstr utility via the pipe operator, and voila
sources:How to find out which application is using what port, Ted Heich
