Checking which programs are choking my bandwidth?

[guhan.web]

When using the system, suddenly the data light on the modem starts blinking fast and on checking the 'system monitor', I find that something is doing a lot of uploading and downloading, though I have no clue which program is doing that.

How to check which programs are using the bandwidth and by how much?

[adrianx]

You could try nethogs.
From man nethogs:

NetHogs is a small ’net top’ tool. Instead of breaking the traffic down per protocol or per subnet, like most such tools do, it groups bandwidth by process - and does not rely on a special kernel module to be loaded. So if there’s suddenly a lot of network traffic, you can fire up NetHogs and immediately see which PID is causing this, and if it’s some kind of spinning process, kill it.

Hope that helps.