ss: show all TCP connections

Filter established TCP connections with process info

ss -tanp | grep ESTAB

More lsof commands

ss: show UDP sockets

ss -ulnp

List UDP listening ports with process names
ss: socket stats summary

ss -s

Print socket usage summary by state
ss: filter by destination port

ss -tnp dst :443

Show connections going TO port 443
Find owner of port

lsof -nP -i :<port>

Show which process owns a port; -nP skips DNS/service name lookups for speed
All listening sockets

lsof -nP -iTCP -sTCP:LISTEN

List every TCP listener with PID, no name resolution; modern: ss -ltnp