netstat + ss reference

Note

ss is the replacement program, replacing deprecated netstat (similar to ip replacing ifconfig).

• The Geek Stuff - netstat command examples

terminology

• socket: TCP/UDP/UNIX
• listening:
• non-listening:

flags

• -t: TCP
• -u:: UDP
• -l: display listening sockets
• -a: display both listening and non-listening
• -p: show process name
• -n: show numeric IP addresses
• -s: show statistics
• -c: print continuously
• -r: print kernel (internal/localhost) routing table
• -o: show timer information
• -4: show only IPv4 connections
• -6: show only IPv6 connections

useful commands

• ss: by default displays open, non-listening sockets (TCP/UDP/UNIX) that have established connections
• ss -tulpn: show TCP and UDP with listening ports, process names, and numeric IP addresses
• ss -co: print default connection information continuously, with timer information
• netstat -co --protocol=inet,inet6: continuously monitor IPv4 and IPv6 connections with timer information
• ss -an | grep ssh: find out what port a particular service is using
• ss -an | grep ':80': find out what service is using a particular port