lsof Cheatsheet
Nice things you can do with lsof # Show all active internet connections lsof -i # Show all active TCP connections lsof -iTCP lsof -iTCP:57123 # Show active TCP connection on port 57123 # Show all active IPv4 connections lsof -i4 lsof -i4:57123 # Show active IPv4 connection on port 57123 # Show all file descriptors for a user lsof -u $USER