Postfix Cyrus Web cyradm HOWTO

10.1. Brief introdcution to viruses

I think I do not need to explain how dangerous Viruses are. Unfortunately in the

most recent attacks from SCO.A (aka MyDoom) also more or less experienced

users get tricked by viruses. Most of todays viruses and worms comes via the

internet, most of them via E Mail. Needless to say, that viruses should be catched

by the SMTP system if possible.

Not a substitute

A mailsystem that filters viruses is NEVER a substitute for a

local installed anti virus software. E Mails are only one way

how viruses can penetrate computers.

10.2. Brief introduction to SPAM

The other harmless but unwanted and disturbing E Mails are SPAM e mails. SPAM

is originally a disgusting canned meat. It is a synonym for UCE (Unsolicited

Commercial Email) and UBE (Unsolicited Bulk Email).

Studies claim, that up to 60 percent of the worldwide e mail traffic is SPAM. Before

I installed the anti SPAM filters on my SMTP servers, I received about 150

SPAMS's a day. One reason is this document. In ancient time, I noticed my real

e mail address unprotected. E mail harvesters are scanning websites allover the

world for addresses, and try to deliver its commercial, often illegal offers.

10.3. Strategy against viruses

The strategy against viruses is pretty forward: Filtering viruses delivered via e mail

and having a localally installed anti virus software.

Almost all vendors of anti virus software have a up to date version for Linux and

Unix Systems, because most SMTP servers are running on Unix. In this document

I'll explain HOWTO implement clamav (http://www.clamav.net), a very active open

source anti virus project.

10.4. Strategy against SPAM

Fighting against SPAM is much more difficult than viruses. Why? It is because

every virus has a unique signature. SPAM can contain arbitrary content. Some of

the SPAM is in english, other is korean, other is in "you name it language".

40