ASSP Anti-Spam Proxy Setup using Postfix

From Debian Wiki

Introduction

ASSP is one of the best Anti-Spam proxy's available today. I have personally been using ASSP for a couple of years now and I have never seen better results in fighting Spam than with ASSP. Other comparative tools such as Spamassassin, Razor, Pyzor and Dcc haven't worked nearly half as good as ASSP which is why this HOWTO has been created for the Debian / Postfix mail server.

ASSP learns as you go along so the longer the system is in place the better and more effective it becomes at blocking spam on the server side.

ASSP stands for Anti-Spam SMTP Proxy and the ASSP wiki describes their product as follows:

"The ASSP server project is an Open Source platform-independent transparent SMTP proxy server that leverages numerous methodologies and technologies to both rigidly and adaptively identify spam. This web site's domain name, "ASSPSMTP", is the common name used for the daemon or service running ASSP."

For more info about ASSP visit http://assp.sourceforge.net or http://www.asspsmtp.org

At the time of creating this HOWTO (15/01/2007) I can report the following Runtime Statistics on my Debian Server running ASSP:

ASSP Proxy Uptime:	14.152 days
Messages Processed:	4278 (302.3 per day)
Non-Local Mail Blocked:	94.1%
CPU Usage:	0.30% avg
Concurrent SMTP Sessions:	6 max

Requirements

A Debian Etch base installation - Installation HOWTO here.
Postfix and Courier - Installation HOWTO here.
Root access to your server.
IMPORTANT: Please read the TODO list at the end of this page before proceeding with installing.

Installing ASSP

ASSP's core is built off of certain required and optional Perl modules. Below is a list of the required and optional Perl modules needed by ASSP:

Perl Module	Requirement
Compress::Zlib	NEEDED - Standard Perl installation
Digest::MD5	NEEDED - Standard Perl installation
Email::Valid	OPTIONAL, BUT ADVISED
File::ReadBackwards	OPTIONAL, BUT ADVISED
Mail::SPF::Query	OPTIONAL
Mail::SRS	OPTIONAL
Net::DNS	NEEDED TO RUN RBL, SPF and 1.2.X
Sys::Syslog	OPTIONAL
Net::LDAP	OPTIONAL :: NEEDED IF YOU RUN LDAP
Time::HiRes	NEEDED - Standard Perl installation

In this HOWTO we're going to install all the Perl modules as follows:

perl -MCPAN -e shell

install Compress::Zlib
install Digest::MD5
install Email::Valid
install File::ReadBackwards
install Mail::SPF::Query
install Mail::SRS
install Net::DNS
install Sys::Syslog
install Net::LDAP
install Time::HiRes

q (to leave the Perl shell)

Now lets install ASSP:

cd /usr/src/
wget -c http://surfnet.dl.sourceforge.net/sourceforge/assp/ASSP_1.2.6-Install.zip
unzip ASSP_1.2.6-Install.zip

Make some preparations:

mkdir -p /usr/share/assp/spam
mkdir /usr/share/assp/notspam
mkdir /usr/share/assp/errors
mkdir /usr/share/assp/errors/spam
mkdir /usr/share/assp/errors/notspam

And put it in place:

mv -f assp.pl ASSP
mv -f ASSP/* /usr/share/assp

Remove the leftovers:

rm -fr ASSP_1.2.6* changelog.txt Install.txt __MACOSX/ README.txt

Set some sane permissions:

chown -R 0.0 /usr/share/assp

Go there and start it up for the first time:

cd /usr/share/assp
perl assp.pl

Now go to the following URL:

http://example.com:55555

and log in with any name and the password nospam4me.

Configuring ASSP

There are a myriad of options available to you in the ASSP web interface however we are only going to configure the core settings. A full breakdown of these settings and the meaning of each one is beyond the scope of this HOWTO and you'll need to do some research on the ASSP website for setting up the other options not described below.

Network Setup Options

Option	Setting	Description
SMTP Destination	125	The internal Postfix
As a Daemon	Tick this box	Runs ASSP as a background daemon
Listen Port	25	The spam proxy
Web Admin Port	XXXXX	Change to a new port number

Relaying Options

Option	Setting	Description
Accept All Mail	example.com	Add all your local domains here
Local Domains	example.com	Add all your local domains here

TestModes Options

Tick every single box in the TestModes option. ASSP needs between 500-1000 emails to learn from before it becomes truly effective so leave it in TestMode until you are positive that all mail is being blocked and filtered correctly.

Security Options

Option	Setting	Description
Run as UID	nobody	The ASSP username to run under
Run as GID	nogroup	The ASSP group to run under
Web Admin Password	newpasword	Change this

Postfix Configuration

Now we need to tell postfix to only accept connections from our proxy.

vim /etc/postfix/master.cf

Change this line:

smtp

inet

n

-

smtpd

To this:

125

inet

n

-

smtpd

Restart postfix:

/etc/init.d/postfix restart

Now lets start things automagicly.

vim /etc/init.d/assp

Add the following:

#!/bin/sh -e
# Start or stop ASSP
#
# Ivo Schaap <ivo@lineau.nl>

PATH=/bin:/usr/bin:/sbin:/usr/sbin

case "$1" in

    start)
        echo -n "Starting the Anti-Spam SMTP Proxy"
        cd /usr/share/assp
        perl assp.pl
    ;;

    stop)
        echo -n "Stopping the Anti-Spam SMTP Proxy"
        kill -9 `ps ax | grep "perl assp.pl" | grep -v grep | awk '{ print $1 }'`
    ;;

    restart)
        $0 stop || true
        $0 start
    ;;
   
    *)
    echo "Usage: /etc/init.d/assp {start|stop|restart}"
    exit 1
    ;;

esac

exit 0

Set the permissions.

chmod 755 /etc/init.d/assp

and add it to the default runlevel.

update-rc.d assp defaults

Have fun with all the options and after a week rebuild the bayes database. Check the directories /usr/share/assp/spam and notspam for wrong entries, if good mail ends up in the spam directory please move it to the notspam directory and vice versa. After that do:

cd /usr/share/assp |

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