As another line of defence you can use is software such as tripwire. It basically works out a hash code for each of your files periodically and alerts you if a file has been modified that shouldn''t be. It''s good for finding out when a machine has been comprimised but you need to be careful to keep the tripwire software safe from alteration by malicious users as well if the data is stored locally because they can cover their tracks.

There are also a number of unix virus scanners that really scan more for Windows viruses. So you''d put the scanner on a mail server and stop viruses before they go out to everybody.

How about a nice GPL''d virus scanner
Apperently its used by Sourceforge.net and some other comerical organisations...
It has experimental support for on access scanning....

http://www.clamav.net/





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Does it matter? Even if it does matter, does it matter that it matters?