Author: [email protected]
It’s easier then it sounds!
This is a quick’n’dirty way to setup AS/AV protection on your MX.
If you’re not familiar with software described here, then take a
look at www.postfix.org,
clamav.elektrapro.com
and www.ijs.si/software/amavisd.
All these goodies are also available trough FreeBSD’s ports collection.
You should, however, spend some time with configuration files, as
they’re tweaked for my server…
Setup described here is running on FreeBSD 4.6-REL (i386) with
Postifx 1.1.11, Clamav 0.60_1 and Amavisd-new 20030616.p5.
Make sure you update your ports before installing the
software!
General overview
In this setup, spam and virus checking is preformed on the same
box.
Here’s the theory:
Postfix accepts mail on port 25 and forwards it to 127.0.0.1:10024
where amavisd-new is listening. Amavisd-new does it magic with
Spamassassin and ClamAV and forwards mail back to postfix instance
running on 127.0.0.1:10025.
Second postfix instance isn’t doing any scanning, just
re-injecting mail into queue.
e-mail --> [postifx (*:25)] --> [amavisd-new (127.0.0.1:10024)] -->
[postfix (127.0.0.1:10025)] --> [delivery agent (local/smtp/...)]
Of course, amavisd-new can run on separate machine. Just adjust
listening and forwarding IP and port.
Setting up ClamAV
As root:
cd /usr/ports/security/clamav && make install clean
Configuration file: /usr/local/etc/clamav.conf.
Startup script: /usr/local/etc/rc.d/clamav.sh
To update ClamAV’s virus database regulary, put something like
this in root’s crontab:
0 6 * * * /usr/local/bin/freshclam
Start clamd.
Setting up Amavisd-new
As root:
cd /usr/ports/security/amavisd-new && make install clean
Configuration file: /usr/local/etc/amavisd.conf
Startup script: /usr/local/etc/rc.d/amavisd.sh
Start amavisd.
Setting up Postfix
Configure postfix as you would normaly. After you’re satisfied,
add these lines:
master.cf:
smtp-amavis unix - - n - 3 smtp
-o smtp_data_done_timeout=1200
-o disable_dns_lookups=yes
127.0.0.1:10025 inet n - n - - smtpd
-o content_filter=
-o local_recipient_maps=
-o relay_recipient_maps=
-o smtpd_restriction_classes=
-o smtpd_client_restrictions=
-o smtpd_helo_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o mynetworks=127.0.0.0/8
-o strict_rfc821_envelopes=yes
main.cf:
content_filter = smtp-amavis:[127.0.0.1]:10024
Restart Postfix (with postfix stop; postifx start) and watch
mail logs for errors. If everything went ok, you shold see clamd
log (/var/amavis/clamd.log) and amavisd log
(/var/amavis/amavis.log) filling up.
You should see additional mail headers in mails which go trough
your mailer (X-Virus-Scanned: and X-Spam-Status:).
$Id: av.html,v 1.8 2003/11/28 09:58:53 damir Exp $
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