Controlling IP traffic (e.g. per month)

[Dieter Heiliger <dieter.heiliger@gmx.de>]

Hi Gurus!

I am doing the administration for a server located at an ISP. We have a 
certain amount of traffic per month included in the monthly fee. 
Additional traffic will be paid extra.

Now I want to get more control over the traffic that was already used 
since the beginning of each month. My ideal configuration would be to 
get an email when e.g. 80% of the traffic included in the monthly fee 
got used already. When a new month begins the counter has to be set to 
zero again.

Is there an easy way to implement this?

Any help is highly appreciated.

TIA

Dieter

--
Dieter Heiliger | dieter.heiliger@gmx.de  (private)
                  dieter.heiliger@sun.com (business)