2 - Raspberry PI Community Projects

This new configuration is taken into account by running /etc/init.d/clamav-milter rest
art.
The standard ClamAV configuration fits most situations, but some important parameters can
still be customized with dpkg-reconfigure clamav-base. Similarly, running dpkg-reconfig
ure clamav-milter allows defining the mail filter's behavior in some detail.
The last step involves telling Postfix to use the recently-configured filter. This is a simple matter
of adding the following directive to /etc/postfix/main.cf:
# Virus check with clamav-milter
smtpd_milters = inet:[127.0.0.1]:10002
If the antivirus causes problems, this line can be commented out, and /etc/init.d/postfix
reload should be run so that this change is taken into account.
IN PRACTICE
Testing the antivirus
Once the antivirus is set up, its correct behavior should be tested. The simplest
way to do that is to send a test email with an aachment containing the
eicar.com (or eicar.com.zip) file, which can be downloaded online:
➨ http://www.eicar.org/anti_virus_test_file.htm
This file is not a true virus, but a test file that all antivirus soware on the
market diagnose as a virus to allow checking installations.
All messages handled by Postfix now go through the antivirus filter.
11.1.7. Authenticated SMTP
Being able to send emails requires an SMTP server to be reachable; it also requires said SMTP
server to send emails through it. For roaming users, that may need regularly changing the
configuration of the SMTP client, since Falcot's SMTP server rejects messages coming from IP
addresses apparently not belonging to the company. Two solutions exist: either the roaming
user installs an SMTP server on their computer, or they still use the company server with some
means of authenticating as an employee. The former solution is not recommended since the
computer won't be permanently connected, and it won't be able to retry sending messages in
case of problems; we will focus on the latter solution.
SMTP authentication in Postfix relies on SASL (Simple Authentication and Security Layer). It requires
installing the libsasl2-modules and sasl2-bin packages, then registering a password in the
SASL database for each user that needs authenticating on the SMTP server. This is done with the
saslpasswd2 command, which takes several parameters. The -u option defines the authentication
domain, which must match the smtpd_sasl_local_domain parameter in the Postfix configuration.
The -c option allows creating a user, and -f allows specifying the file to use if the
SASL database needs to be stored at a different location than the default (/etc/sasldb2).
# saslpasswd2 -h `postconf -h myhostname` -f /var/spool/postfix/etc/sasldb2 -c jean
[... type jean's password twice ...]
266 The Debian Administrator's Handbook