I use a 3G cellular Internet connection with a very strict traffic limit, but some times I go to office and use an unlimited and fast cable connection (and of course I do traffic-consuming operations, like updating the system there).
I'd like to keep track of how much have I already downloaded using the mobile connection (so, it can either filter by interface or be easily suspendable so that I can pause it when I use an unlimited line) this month (so, the counter most not reset when I reboot my laptop or reconnect, I'd lile to only reset it manually).
What's the easiest way to do this in Ubuntu 10.10?
I wouldn't like to set up any complex monitoring/billing systems.