How to find out which software is secretly consuming my bandwidth

To find out how much bandwidth I use everyday, I installed NetWorx, a monitor software, on my laptop.

To my surprise, even if I turned of all software that might use Internet, NetWrox still reports that my laptop downloaded 270MB in an hour. Considering my monthly download limitation is only 100GB, that's unacceptable.

How can I find out which software is secretly stealing my bandwidth?

Solution 1:

Have a play with TCPView, part of the excellent Sysinternals suite.

Solution 2:

If you are running Windows 7, the built-in resource monitor is good for a quick overview:

For more verbose statistics, Netlimite Monitor (free version) is even better for analyzing usage patterns:

The paid version allows you to throttle applications. Netlimiter Monitor is not yet available for Windows 7, although coming soon according to the download page (Netlimiter Monitor v3).