Find Which Process Owns a Port in Linux

When a service cannot start because a port is already in use, the first step is to identify which process is listening on that port.

Using ss

ss -ltnp

This lists listening TCP ports and the process information where available.

Using lsof

lsof -i :8080

Replace 8080 with the port you are checking.

Older systems

netstat -tulpn

ss is generally preferred on modern Linux systems, but netstat may still be available on older servers.