Windows – How to know which Windows application does listen on a particular TCP port?

networkingPROXYtcpipwindowswindows 7

I have been using a personal HTTP proxy to remove ads and boost caching for a while but have then noticed that my Firefox still works when the proxy application is shut down (while the browser is configured to use proxy at 127.0.0.1:8080). Looks like there is another proxy running on my PC, perhaps even malicious. How to detect it?

Best Answer

first to answer your title, run this command in powershell as admin:

netstat -abno | findstr LISTENING

the last column will be the process ID of the app that owns the port. you can then crossref it with Tasklist

tasklist | findstr <PID>

Multiple apps cannot bind to a single port, so if the browser is configured to use localhost:8080, and you had a known application listening on that port, the unknown app you suspect could not be running at the same time. if there is some other app, it would have had to claim the port after your known proxy closed.