Trafmetux is a network traffic meter for Linux. It
tells you how much IP traffic has been seen by the
Linux kernel module during the last few minutes,
hours, days, weeks, and months. It's very useful
when you have a limited Internet connection with
quotas. For instance, many mobile broadband ISP
provide only 3GB/month. In that case, you need to
know how many megabytes you already used.