I have a usb 3g dongle which I use from time to time by plugging it into my router so that all computers on the network can use the 3g connection (as opposed to plugging the usb into a single computer).
This 3g dongle has a monthly data limit on it which if exceeded, any data used over the limit is extremely expensive. So I need a way to track how much data/bandwidth is used when the 3g is plugged into the router so that I know when to stop using it.
After some searching I found applications like darkstat and bandwidthd but from what I can tell, these tools monitor network traffic all the time. What I need to be able to do is switch the monitoring on/off only when im using the 3g.
Basically I need to be able to plug the 3g into the router and then start the bandwidth monitor, then stop the monitor when i've unplugged it. I need to then be able to keep an ongoing record of how much bandwidth has been used each month.
It's ok if I have to add up the totals manually each time I plug in the 3g to keep a monthly running total. However if there is something that does that automatically that would be great.