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Recently a large number of clients have been shocked to hear that they are apparently using more than their allocated bandwidth. Various ISP's have different ways of billing their clients for usage. Some ISP's only charge for International traffic used during business hours. Some ISP's charge for all traffic that passes along the broadband link. Either way, most ISP's traffic logging software is of a very high standard and is thoroughly tested for accuracy.

There are numerous programs which can be installed on a Linux server to monitor the traffic usage, but unless you have the exact software which your ISP has, and unless you have configured it exactly how they have configured their software, it is highly unlikely that the total traffic results will match up exactly.

We therefore advise clients that logging software which is installed on their Linux servers should be taken as a guide line. In most cases there will be a discrepancy in the figures.

One system which can be used as a guideline is the built in Bandwidth monitoring tool which comes with the Webmin application. If you already have Webmin installed, you will find the tool under Networking. Once enabled, it will allow you to display traffic usage based on various options. Please remember that these results should only be taken as a guideline.

There are numerous ways to cut back on bandwidth usage on your network. The main culprits which generate large volumes of traffic are.

1. Windows updates
2. Antivirus updates
3. Machines infected with Internet Worms
4. Movie or Music downloads using Peer-to-Peer software.

The best way to cut back on usage is to avoid running updates during the day, they can be scheduled to run overnight. Obviously client machines should be checked regularly for virus infections. Peer-to-Peer software should be avoided if possible, otherwise it should be monitored and only used after hours.