How to find what is using a port on Linux

Linux tells you who owns a socket via ss, lsof, or an agent that already enumerated listeners.

With PortPilot

1. Install and run portpilot ports (or the desktop Ports view).
2. portpilot port <n> shows process identity, bind address, and relations (Docker publish, reverse proxy) when detected.
3. Pair the host if you want the same view in the website.

Classic commands

ss -lptn 'sport = :3000'
sudo lsof -iTCP:3000 -sTCP:LISTEN

PortPilot keeps history when the process later disappears — ss does not.

Next

• Check open ports on Linux
• Docker ports
• Download