I’ve got a list of tools I think are cool or useful, so I’m going to start sharing my thoughts of them here….isn’t that the point? So today’s tool is iftop. It can be used to display bandwidth usage on an interface. If you can’t figure out what it does based on the name, their description of the tool lays it out well:
iftop does for network usage what top(1) does for CPU usage. It listens to network traffic on a named interface and displays a table of current bandwidth usage by pairs of hosts. Handy for answering the question “why is our ADSL link so slow?”.
Small and simple tool, what’s not to like. Real good for those times that you know something is eating traffic but don’t know what. Check out screenshots of iftop at http://www.ex-parrot.com/~pdw/iftop/.