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 " " | uniq
When 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:
COMMANDAppleVNCSPTHPastebSystemUISaosnotifyiTunesGrowlHelpTransmitiChatAgenfirefox-bVPNClientMail
The first row, COMMAND, is just the column header. Below that are the processes that are using the Internet connection. Most of the time, they are self-explanatory, or can be figured out with relative ease. On my list, most of the entries are pretty clear, but perhaps not aosnotify. A bit of work with…