Thursday, April 30, 2009

Spam Filtering at DePauw

Contributed by Michael Gough, Instructional Technologist and Coordinator of START and Bernie Timberman, Senior Network and Systems Administrator

Spam is becoming more prevalent in the cyber community every day. Many viruses and identity thieves rely upon spam email to spread their schemes. Therefore, to prevent many viruses and possible spyware infections, DePauw has invested in two robust spam filters. These filters work very well, especially given the volume of emails that come into DePauw. However, it is not perfect and users should still scan attachments for viruses and spyware. Also, be careful when clicking on links in emails; many spammers use these links to take you to Web sites that can steal information from your computer.

The following offers a perspective of how much of our email really is spam, helps you understand how this system works, and give you an idea of how your contributions can assist our spam filter system.

DePauw uses two Barracuda Model 400 spam filters to trap spam, viruses, and Denial of Service attacks. Denial of Service attacks are email attacks that are designed to overwhelm an email server and deny its functionality for its users. Our filters are configured to update their spam and virus definitions hourly. This information is combined with known spam messages identified by the HelpDesk. Below is a graph from one of the filter’s recent performances.

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Notice how only a very small fraction of the total is allowed to be delivered to the recipients' email boxes. The spam filters actually have a 12 step defense layer and a load balancer equalizes the work between the two filters so that one of them is not overwhelmed with too much volume.
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The last step (Spam Scoring) is modified daily by the DePauw community. We input spam messages that are received by the HelpDesk from users to strengthen the spam filtering. Therefore, you can help our filters become more efficient by sending any spam that you recieve to the HelpDesk. This will help all computer users prevent viruses and cybercrime on DePauw’s campus.