Centos 7 | Postfix + Amavisd-new + ClamAV + Spamassassin

[paknet]

Install Amavisd-new


Ok. Here we go…

Code:

yum install amavisd-new

This will install amavisd-new and a bunch of dependencies (30Mb)
It will also install Spamassassin by default

Install ClamAV

Code:

yum install clamav clamav-update

edit the following file

Code:

vi /etc/freshclam.conf

and comment the line “Example” like this

Code:

# Example

update the ClamAV database

Code:

freshclam

auto update is already set up, but to work properly, we need to edit the following file:

Code:

vi /etc/sysconfig/freshclam

and remove this 4 lines:

Code:

### !!!!! REMOVE ME !!!!!!
### REMOVE ME: By default, the freshclam update is disabled to avoid
### REMOVE ME: network access without prior activation
FRESHCLAM_DELAY=disabled-warn   # REMOVE ME

edit the cron file just to make sure that the line is not commented

Code:

vi /etc/cron.d/clamav-update

OK. Packages are installed. Here comes the configuration part

Configuration

We need to edit amavisd.conf file

Code:

vi /etc/amavisd/amavisd.conf

Change the following lines like this…

Code:

$mydomain = ‘domain.com’;   # a convenient default for other settings
$myhostname = 'mail.domain.com’;  # must be a fully-qualified domain name and same as reverse DNS lookup

Now we need to check if everything is set in postfix master.cf

Code:

vi /etc/postfix/master.cf

On top you should have lines…

Code:

smtp      inet  n       -       n       -       -       smtpd
 -o smtpd_sasl_auth_enable=yes
 -o receive_override_options=no_address_mappings
 -o content_filter=smtp-amavis:127.0.0.1:10024

…and on the bottom of the file…

Code:

#
# spam/virus section
#
smtp-amavis  unix  -    -       y       -       2       smtp
 -o smtp_data_done_timeout=1200
 -o disable_dns_lookups=yes
 -o smtp_send_xforward_command=yes
127.0.0.1:10025 inet n  -       y       -       -       smtpd
 -o content_filter=
 -o smtpd_helo_restrictions=
 -o smtpd_sender_restrictions=
 -o smtpd_recipient_restrictions=permit_mynetworks,reject
 -o mynetworks=127.0.0.0/8
 -o smtpd_error_sleep_time=0
 -o smtpd_soft_error_limit=1001
 -o smtpd_hard_error_limit=1000
 -o receive_override_options=no_header_body_checks
 -o smtpd_helo_required=no
 -o smtpd_client_restrictions=
 -o smtpd_restriction_classes=
 -o disable_vrfy_command=no
 -o strict_rfc821_envelopes=yes

Stop the postfix daemon

Code:

systemctl stop postfix

First we need to make sure that Spamassassin, Amavisd-new and ClamAV daemons are running

Code:

systemctl start spamassassin
systemctl start amavisd # This will also run ClamAV

Then make sure that after reboot all daemons are automatically started:

Code:

systemctl enable spamassassin
systemctl enable amavisd

Now start the postfix daemon:

Code:

systemctl start postfix

If all is well, we should have a basic spam and virus protection up and running!
Let's do some testing:

Test Amavisd…

Code:

telnet localhost 10024
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 [::1] ESMTP amavisd-new service ready
ehlo localhost
250-[::1]
250-VRFY
250-PIPELINING
250-SIZE
250-ENHANCEDSTATUSCODES
250-8BITMIME
250-DSN
250 XFORWARD NAME ADDR PORT PROTO HELO IDENT SOURCE

OK. 

Test the SMTP daemon on port 10025

Code:

telnet localhost 10025
Trying ::1...
telnet: connect to address ::1: Connection refused
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
220 mail.domain.com ESMTP
ehlo localhost
250-mail.domain.com
250-PIPELINING
250-SIZE 20480000
250-VRFY
250-ETRN
250-STARTTLS
250-AUTH PLAIN LOGIN
250-AUTH=PLAIN LOGIN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN

OK.

Daemons are up and running. It's time to send some viruses and spam to test our server.

Keep an eye on maillog file while receiving virus and spam

Code:

tail -f /var/log/maillog

Send an email from external account (gmail) to account hosted on this server with the following content (Eicar virus) :

Code:

X5O!P%@AP[4\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*

You should see something like this in your maillog file…

Code:

Feb 00 00:00:00 host amavis[32426]: (032426-01) Blocked INFECTED (Eicar-Test-Signature) {DiscardedOpenRelay,Quarantined}

Woohoo, Amavis, ClamAV and Postfix are working together nicely!

What about SPAM? Send the following string from external account:

Code:

XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X

Check the maillog…

Code:

Feb 00 00:00:00 host amavis[32425]: (032425-02) Blocked SPAM {DiscardedOpenRelay,Quarantined}

Blocked!

One last thing to do… Spamassassin already added a cron job. Just make sure that the line is not commented!

Code:

vi /etc/cron.d/sa-update

Thats it! Job well done.