TL;DR: How to find which program is using a port, and stop it

KB ID 2610140006

Problem: A program, web server or container will not start because its port is already taken, and you need to find what is using the port and stop or reconfigure it.
Applies to: netstat, PowerShell NetTCPIP cmdlets, tasklist, sc.exe, netsh (Windows); ss, lsof, fuser, systemctl (Linux)
Time to fix: 5 to 15 minutes

Symptoms, platforms, difficulty and more

Symptoms: "Address already in use" or "bind() failed (98: Address already in use)" on Linux. "Only one usage of each socket address (protocol/network address/port) is normally permitted" or "Port 80 is already in use" on Windows. A web server, database or dev tool that exits at startup, or a port that looks free but cannot be used.
Platforms affected: Windows 10, Windows 11, Windows Server, Linux
Difficulty: Intermediate (command line, administrator or root for some steps)
Verified on: Linux part run on Omarchy (Arch Linux), 14 October 2026: iproute2 ss 7.2.0, lsof 4.99.7, psmisc fuser 23.7, systemd 261. Tested with a throwaway python3 -m http.server 18765 –bind 127.0.0.1: ss -ltnp, ss with a sport filter, lsof -i :18765, lsof -nP -iTCP:18765 -sTCP:LISTEN, fuser 18765/tcp and fuser -v, ps on the PID, systemctl status against a shell's PID, starting a second listener on the same port (python3 raised OSError 98, Address already in use), then stopping the listener with kill and confirming the port was free. Also confirmed without sudo that ss shows no process for other users' listeners, and that lsof and fuser print nothing for them. fuser -k and systemctl stop were not run. The Windows parts were not tested; they were checked against Microsoft Learn.
Category: How-to
Updated: 14 Oct 2026
Tags: Linux, Networking, Ports, Troubleshooting, Windows

The fix only. No explanation, no diagnosis. Read the full article if any of this does not match what you are seeing.

Get-NetTCPConnection -LocalPort 80 -State Listen | Select-Object OwningProcess
Get-Process -Id <PID>

Is it a service? Get-CimInstance Win32_Service -Filter "ProcessId=<PID>"
Stop it: Stop-Service -Name <name>, or for a plain program Stop-Process -Id <PID> -Confirm.
Linux: sudo ss -ltnp 'sport = :80', then systemctl status <PID>, then sudo systemctl stop <unit> or kill <PID>.
Run the check again to confirm the port is free.

Do not kill PID 4, svchost.exe, lsass.exe or anything you cannot name. A shared svchost.exe hosts several services.

No process listed? Check netsh interface ipv4 show excludedportrange protocol=tcp and netsh http show servicestate.

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Updated on October 14, 2026