View Used Ports

There are a few different options for showing TCP ports that are being listened on:

$ sudo ss -tulpn | grep LISTEN
$ sudo lsof -i -P -n | grep LISTEN
$ sudo netstat -tulpn | grep LISTEN

If you want to search for a specific port, you can run the same commands as above and just grep for the port number. You can also run this command that’s slightly different:

$ sudo lsof -i:<PORT>