When developing or using services it’s often handy to list all listening sockets or connections on the machine. We have a handy tool at our disposal on most distributions:
On older distributions there was the
netstattool, but on newer distribution it’s been replaced byss.
$ ss
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port
u_seq ESTAB 0 0 @0001f 101956 * 101957
u_seq ESTAB 0 0 @0001c 36327 * 36328
u_str ESTAB 0 0 * 605506 * 605507
u_str ESTAB 0 0 /var/run/dbus/system_bus_socket 40972 * 39126
u_str ESTAB 0 0 * 39939 * 39938
u_str ESTAB 0 0 * 29377 * 27430
u_str ESTAB 0 0 * 620557 * 620556
u_str ESTAB 0 0 * 602348 * 602349
u_str ESTAB 0 0 * 34852 * 32327
u_str ESTAB 0 0 @/tmp/.X11-unix/X0 27347 * 33301
u_str ESTAB 0 0 /run/user/1000/bus 34057 * 34056
u_str ESTAB 0 0 @/tmp/dbus-RiJ4OUll 1096107 * 1100088
u_str ESTAB 0 0 * 681622 * 681621
u_str ESTAB 0 0 * 107612 * 106793
u_str ESTAB 0 0 * 36029 * 34234
u_str ESTAB 0 0 /run/systemd/journal/stdout 30269 * 35283
u_str ESTAB 0 0 * 35859 * 32413
....a few of my most used options:
-n, --numeric
Do not try to resolve service names.
-a, --all
Display both listening and non-listening (for TCP this means established connections) sockets.
-l, --listening
Display only listening sockets (these are omitted by default).
-p, --processes
Show process using socket.
-t, --tcp
Display TCP sockets.
-u, --udp
Display UDP sockets.
-x, --unix
Display Unix domain sockets (alias for -f unix).Examples:
-
Show all listening tcp sockets (use numeric instead of service names for ports):
ss -altn -
Show all processes with listening tcp sockets (use numeric instead of service names for ports):
ss -altnp
Be aware that you’ll have to execute with
sudofor some operations, like showing processes.