**netstat** (Network Statistics) is useful to query the state of your network connections. It is available for Linux, Windows and MacOS. Run `netstat` from the console of your server. Useful command switches are: **-u** : Show UDP sockets **-p** : Show the PID and name of the program to which each socket belongs. **-l** : Show only listening sockets. **-n** : Show numeric addresses. **-t** : Show TCP sockets Example: $ netstat -uplnt Active Internet connections......