Servers 101: Emailify Your Server Part 6: clamav

In the previous part, we configured SpamAssassin to help ourselves a little bit with spam. Now we are going to install and configure ClamAV as an antivirus for our email. This is completely optional, as you should have an antivirus in your computer and take this load off of your server! This can make a big difference on how powerfull the server you need to rent.

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Other stuff in the Server 101 series:

• Intro and getting into your server - Single Article
• Basic Server Security - 3 Parts
• Setting up a Web Server - 4 Parts
• Managing Your Server - 4 Parts
• caddy - Lightweight Web Server - 1 Part

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Installing clamav

apt-get install clamav clamav-daemon clamsmtp

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Configuring ClamSMTP

Edit clamsmtp.conf: nano /etc/clamsmtpd.conf

We need to uncomment the line reading Header: X-AV-Checked: ClamAV using ClamSMTP. Just remove the hashtag (#) infront of it!

In the same file, we need to change the user clamsmtp will run as. Locate User: clamsmtp and change it to User: clamav.

Save and exit.

Now we have to change the owner of a couple of folders

chown -R clamav:clamav /var/spool/clamsmtp 
chown -R clamav:clamav /var/run/clamsmtp

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Configuring Postfix to use clamsmtp

We now need to edit main.cf: nano /etc/postfix/main.cf

add this line at the end:

content_filter = scan:127.0.0.1:10026

Save and exit (the IP and port above, are the default for clamsmtp).

Now, we move to the master.cf: nano /etc/postfix/master.cf

Copy and paste these lines at the end of the file:

scan unix -       -       n       -       16       smtp
   -o smtp_data_done_timeout=1200
   -o smtp_send_xforward_command=yes
   -o disable_dns_lookups=yes
127.0.0.1:10025 inet n       -       n       -       16       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_style=host
   -o smtpd_authorized_xforward_hosts=127.0.0.0/8

Save and exit!

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Restart!

Restart clamav-daemon, clamsmtp and postfix:

service clamav-daemon restart
service clamsmtp restart
service postfix restart

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We are done! clamav is already updating the virus definitions in the background via freshclam, and will be checking our emails via clamsmtp.

This post concludes the "Mailify series".

• Main post image source: Pestaola.gr

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