ss

Find out which ports are open and who listens on them

What it does

ss shows network connections. -tlnp answers the common question "who took this port": TCP (-t), only those waiting for connections (-l), ports as numbers (-n), and the program holding them (-p; other users' programs are shown only with sudo).

In the address column, 0.0.0.0:80 means the port is open on every interface, and 127.0.0.1:5432 only to the machine itself. To check one port, add | grep :80. ss replaced netstat, and their flags are nearly the same.

Syntax

sudo ss -tlnp
sudo ss -tlnp | grep :<port>

Examples

• Find out which programs listen on TCP ports

  sudo ss -tlnp

  same as: sudo ss -ltnp, sudo ss -tnlp, sudo ss -lntp, sudo ss -plnt

  • ss — network sockets
  • -t — TCP only
  • -l — listening ports only
  • -n — ports as numbers, not names
  • -p — which process; with sudo, everyone's

Related commands

• ip — See network interfaces and addresses
• systemctl — Manage services: start, stop, start at boot
• curl — Send an HTTP request from the terminal

Practise · All commands