You sometimes want to check if a program that you've installed is doing anything funky. While you could install a full-blown packet analyser like WIreshark, sometimes, that is overkill. A quicker and handier option would be to just rely on good old netstat. Like so:
netstat -bn 10
as well as
netstat -bf 10
-b: displays the program name (executable)
-n: displays the IP address
-f: displays the resolved form of the IP address
10: indicates that the command should be repeated after 10 seconds
Hope this helps!