ss

Additional Notes

ss shows socket information: listening ports, established connections, TCP/UDP state, and process ownership when permitted.

It is the modern replacement for many netstat use cases and is usually faster.

Syntax

ss [options]

Parameters

• options: Flags that change how ss behaves.

Common Options

• -t: TCP sockets.
• -u: UDP sockets.
• -l: Listening sockets.
• -n: Numeric addresses and ports.
• -p: Show process information.
• -a: Show listening and non-listening sockets.
• -r: Resolve hostnames.
• -s: Show socket summary.

Examples

ss -tuln

Show listening TCP and UDP ports numerically.

sudo ss -tulnp

Show listening ports with process names.

ss -tan

Show all TCP sockets numerically.

ss -s

Show socket summary.

ss -tn state established

Show established TCP connections.

Practical Notes

• Use sudo with -p when process names are hidden.
• 127.0.0.1:PORT listens only locally; 0.0.0.0:PORT listens on all IPv4 interfaces.
• Use systemctl status service after identifying a service port.
• ss -tuln is one of the quickest port-inspection commands on modern Linux.