ss
"ss - another utility to investigate sockets" - man ss
This tool shows all sockets, not just networking sockets.
Examples
Options can be concatenated, so ss -t -n -l -p can be ss -tnlp
Show all established connections, don't resolve service names
ss -n
Show all listening sockets
ss -l
Display all TCP sockets
ss -t -a
Show ipv4 listening sockets sorted by port
ss -4 -ltn | sort -k2 -t: -n
Show ssh connections
ss -at '( sport = :ssh or dport = :ssh )'
Show ipv4 sockets in a particular state
ss -t4 state time-wait
Show the processes for listening ipv4 sockets
ss -lt4p