How to use the Terminal to see what Mac processes are accessing the internet

If you’ve ever wondered about which programs are using your internet connection at any point in time, here’s one way to find out using Terminal. Open Terminal, in Applications > Utilities, and run this command:
lsof -P -i -n | cut -f 1 -d " " | uniqWhen you press return, you’ll see a list of processes that are using the internet connection. At the time I wrote this, my output looked like this:
COMMAND
AppleVNCS
PTHPasteb
SystemUIS
aosnotify
iTunes
GrowlHelp
Transmit
iChatAg