If you can get hold of the socket it uses, you can use getsockopt to request TCP_INFO; it will return a structure with a number of interesting things (such as the last sent and last received sizes). There's an example at http://linuxgazette.net/136/pfeiffer.html .

With the huge caveat that I haven't tried this myself, and I'm just guessing from the field names what they are.

There are 2 commands that could help you. These are netstat and tcpdump. Check out the links in order to see how they are used.

Regards,

Andrés Miguel 

http://www.tecmint.com/12-tcpdump-commands-a-network-sniffer-tool/

http://www.thegeekstuff.com/2010/03/netstat-command-examples/

A very simple way is looking at the proc folder, many of the scripts running on linux do that.

cat /proc/net/dev

look around this folder, have a lot of cool information

Dear all,

Thank you to your beautiful suggestions. Finally, I chose tcpdump for the work. It helps a lot !