Qmail-Scanner and ClamAV HowTo


Steve Peace

<qmail_clamav_(at)_yahoo_dot_com>

Gregory L. Porter

The_Porter_Davis_Group
<greg@porterdavis.org>
09/19/2004

Revision History
Revision 1.0 09/19/2004 glp
Initial Release, reviewed by TLDP
Revision 0.9 08/01/2004 glp
Converted to DocBook
Revision 0.4 07/01/2004 srp
First public draft in html

Abstract
This HOWTO describes how to integrate ClamAV, an anti-virus attachment scanner
and Qmail-Scanner, an anti-virus message content scanner, with an existing
installation of a qmail email server.
-------------------------------------------------------------------------------
Table of Contents


  1._Introduction


        1._What_This_Document_Is:

        2._What_This_Document_Is_Not:

        3._Acknowledgments

        4._Copyright

        5._Disclaimer

        6._News


  2._Prerequisites

  3._ClamAV


        1._What_is_ClamAV?

        2._Installing_ClamAV

        3._Testing

        4._Updating_Defs

        5._Setting_up_Clamd_and_Using_With_Daemontools


  4._Qmail-Scanner


        1._What_Is_Qmail-Scanner?

        2._Installing_Qmail-Scanner_Prerequisites


              2.1._Maildrop

              2.2._Perl_Modules

              2.3._Mark_Simpson's_TNEF_Unpacker

              2.4._Patching_qmail


        3._Installing_Qmail-Scanner

        4._Ownership

        5._Testing


  5._Configuring_qmail_to_Use_qmail-scanner-queue.pl


        1._Changing_Your_Tcp_Rules

        2._Increasing_Your_Softlimit


  6._Conclusion

  A._Recommended_Reading_and_Other_Resources

  B._Scripts

  C._Software

  D._GNU_Free_Documentation_License


        1._PREAMBLE

        2._APPLICABILITY_AND_DEFINITIONS

        3._VERBATIM_COPYING

        4._COPYING_IN_QUANTITY

        5._MODIFICATIONS

        6._COMBINING_DOCUMENTS

        7._COLLECTIONS_OF_DOCUMENTS

        8._AGGREGATION_WITH_INDEPENDENT_WORKS

        9._TRANSLATION

        10._TERMINATION

        11._FUTURE_REVISIONS_OF_THIS_LICENSE

        12._ADDENDUM:_How_to_use_this_License_for_your_documents




Chapter 1. Introduction

Table of Contents


  1._What_This_Document_Is:

  2._What_This_Document_Is_Not:

  3._Acknowledgments

  4._Copyright

  5._Disclaimer

  6._News


1. What This Document Is:

This document started out as a way for me to document the procedure and
required readings for re-creating the deployment of Qmail-Scanner and ClamAV
for my employer's email system. I am not a writer, or a programmer. I am a
lowly little systems administrator that got frustrated looking online for all
of the information to make Qmail-Scanner work with ClamAV. This HOWTO will
document the steps that I took to get Qmail-Scanner and ClamAV to work
together. Is this the right way to do it? Who knows, it worked for me. There
are plenty of snippets of information that I "liberated" from many sources.
Please see the Acknowledgments. The most current version of this document can
be found at http://stevepeace.no-ip.org.

2. What This Document Is Not:

This document is not a comprehensive source of information for ClamAV, Qmail-
Scanner, qmail, daemontools, Linux, Un*x, FreeBSD, Perl, etc. I do not pretend
to know everything about everything. Like I said before, this worked for me it
may not work for you. If you don't know how to use a particular OS, tool, or
piece of software, THIS HOWTO WILL NOT HELP YOU! I am a firm believer in RTFM.
So please make sure that you check out Appendix A, and the Disclaimer before
following this HOWTO.

3. Acknowledgments

I would like to acknowledge the following people and groups:

Jason Haar (for Qmail-Scanner)
Jesse D. Guardiani (original clamd+daemontools HOWTO)
The entire ClamAV group (for ClamAV)
Dan Bernstein (for qmail and daemontools)
Dave Sill (for lfwq)
Bruce Guenter (qmailqueue patch)
Mark Simpson (TNEF unpacker)
Double Precision Inc. (maildrop)
CPAN.org (Perl modules)


4. Copyright

Copyright (c) 2004 Steven R. Peace.
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU_Free_Documentation_License, Version 1.2 or any later version
published by the Free Software Foundation; with no Invariant Sections, with no
Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included
in the section entitled "GNU Free Documentation License".
This HOWTO is free documentation; you can redistribute it and/or modify it
under the terms of the GNU Free Documentation License. This document is
distributed in the hope that it will be useful, but without any warranty;
without even the implied warranty of merchantability or fitness for a
particular purpose.

5. Disclaimer

I disavow any potential liability for the contents of this document. Use of the
concepts, examples, and/or any other information or content of this document is
entirely at your own risk.
All copyrights are owned by their owners, unless specifically noted otherwise.
Use of a term in this document should not be regarded as affecting the validity
of any trademark or service mark.
Naming of particular products or brands should not be seen as endorsements.
You are strongly recommended to take a backup of your system before major
installation and backups at regular intervals.

6. News

The document home page can be found at http://stevepeace.no-ip.org. Check here
for the most current versions.


Chapter 2. Prerequisites

You should already have a working qmail server with daemontools installed. Your
server will also need:
ClamAV Prerequisites:

Zlib and zlib-devel packages
Gcc compiler (2.9x or 3.x)
Bzip2 library (recommended)

Qmail-Scanner Prerequisites:

qmail 1.03
Reformmime from Maildrop 1.3.8+
Perl 5.005_03+
Perl module Time::HiRes
Perl module DB_File
Perl module Sys::Syslog
Mark Simpson's TNEF Unpacker
Bruce Guenter's QMAILQUEUE patch



Chapter 3. ClamAV

Table of Contents


  1._What_is_ClamAV?

  2._Installing_ClamAV

  3._Testing

  4._Updating_Defs

  5._Setting_up_Clamd_and_Using_With_Daemontools


1. What is ClamAV?

From the ClamAV website:
"Clam AntiVirus is a GPL anti-virus toolkit for UNIX. The main purpose of this
software is the integration with mail servers (attachment scanning). The
package provides a flexible and scalable multi-threaded daemon, a command line
scanner, and a tool for automatic updating via Internet. The programs are based
on a shared library distributed with the Clam AntiVirus package, which you can
use with your own software. Most importantly, the virus database is kept up to
date."

2. Installing ClamAV

Download the ClamAV source at http://www.clamav.net. As of the writing of this
HOWTO, the latest version is 0.65.

  #tar -xvzf clamav-0.65.tar.gz
  #cd clamav-0.65 #groupadd clamav
  #useradd clamav -g clamav -c "Clam AntiVirus" -s /nonexistent .
  #/configure
  #make
  #make install
  #cd ..
  			


3. Testing

As long as make and make install have finished without errors, you are now
ready to test your installation (If you did experience errors, please review
the ClamAV documentation that was included in the tar ball. You may also try
the ClamAV website for some helpful tips). To test your installation type:

  #clamscan -r -l scan.txt clamav-0.65

Clamscan should find a test virus (This is NOT a real virus) in the clamav-
0.65/test directory and log it to the scan.txt log file.
Now you need to configure the ClamAV daemon, clamd, for testing.

  #vi /usr/local/etc/clamav.conf

Comment out "Example" line in clamav.conf and save.

  #clamdscan -l scan.txt clamav-0.65

This should provide output that is similar to the clamscan command you entered
above.

4. Updating Defs

Now we need to update our virus definitions. Clamscan includes a utility,
freshclam, to take care of this. Freshclam automatically changes from root to
the clamav user that you created during the installation. First, create a log
file that freshclam can log to.

  #touch /var/log/clam-update.log
  #chmod 600 /var/log/clamupdate.log
  #chown clamav /var/log/clamupdate.log

Now start freshclam:

  #freshclam -d -c 6 -l /var/log/clam-update.log
  			

This checks for a new virus definition database six (6) times a day. Check the
/var/log/clam-update.log file. It should look something like this:

  -----------------------------------------------------------------------------
  ------------------------
  ClamAV update process started at Wed Jan 28 17:49:48 2004
  main.cvd is up to date (version: 19, sigs: 19987, f-level: 1, builder: ddm)
  daily.cvd updated (version: 111, sigs: 597, f-level: 1, builder: tomek)
  Database updated (20584 signatures) from database.clamav.net (81.4.91.185).
  -----------------------------------------------------------------------------
  ------------------------
  			

Now add the freshclam -d -c 6 -l /var/log/clam-update.log to your startup
scripts.
You can also setup a cronjob to update the Defs every 6 hours, if you like.

  #vi /etc/crontab
  			


  0 6 * * * root /usr/local/bin/clamscan
  			


5. Setting up Clamd and Using With Daemontools

Edit /etc/clamd.conf and make the following changes.

  #vi /etc/clamd.conf


Uncomment "LogSyslog"
Uncomment "StreamSaveToDisk"
Uncomment "MaxThreads" and change value to "30"
Uncomment "User" and change value to "qscand"
Uncomment "Foreground"
Uncomment "ScanMail"

Create the clamav directory.

  #mkdir -p /usr/local/clamav/bin

Now create a startup/shutdown script for clamd. Copy and paste the script shown
below. This script was written by Jesse D. Guardiani.


  #vi /usr/local/clamav/bin/clamdctl

  #!/bin/sh

  # For Red Hat chkconfig
  # chkconfig: - 80 30
  # description: the ClamAV clamd daemon

  PATH=/usr/local/clamav/bin:/bin:/usr/bin:/usr/local/bin:/usr/local/sbin
  export PATH

  case "$1" in
    start)
      echo "Starting clamd"
      if svok /service/clamd ; then
        svc -u /service/clamd
      else
        echo clamd supervise not running
      fi
      if [ -d /var/lock/subsys ]; then
        touch /var/lock/subsys/clamd
      fi
      ;;
    stop)
      echo "Stopping clamd..."
      echo "  clamd"
      svc -d /service/clamd
      if [ -f /var/lock/subsys/clamd ]; then
        rm /var/lock/subsys/clamd
      fi
      ;;
    stat)
      svstat /service/clamd
      svstat /service/clamd/log
      ;;
    restart)
      echo "Restarting clamd:"
      echo "* Stopping clamd."
      svc -d /service/clamd
      echo "* Sending clamd SIGTERM and restarting."
      svc -t /service/clamd
      echo "* Restarting clamd."
      svc -u /service/clamd
      ;;
    hup)
      echo "Sending HUP signal to clamd."
      svc -h /service/clamd
      ;;
    help)
      cat <<HELP
     stop -- stops clamd service (smtp connections refused, nothing goes out)
    start -- starts clamd service (smtp connection accepted, mail can go out)
     stat -- displays status of clamd service
  restart -- stops and restarts the clamd service
      hup -- same as reload
  HELP
      ;;
    *)
      echo "Usage: $0 {start|stop|stat|restart|hup|help}"
      exit 1
      ;;
  esac

  exit 0


  			

Make clamdctl an executable and link to path:

  #chmod 755 /usr/local/clamav/bin/clamdctl


  #chown clamav /usr/local/clamav/bin/clamdctl


  #ln -s /usr/local/clamav/bin/clamdctl /usr/local/bin

Create the supervise directories for the clamd service:

  #mkdir -p /usr/local/clamav/supervise/clamd/log

Now you must create the /usr/local/clamav/supervise/clamd/run file, or just
copy and paste the script shown below. This script was also created by Jesse D.
Guardiani:

  vi /usr/local/clamav/supervise/clamd/run

  #!/bin/sh
  #
  # --------------------------------------------------
  # run
  #
  # Purpose     - Start the clamd daemon/service.
  #
  # Author      - Jesse D. Guardiani
  # Created     - 09/10/03
  # Modified    - 09/25/03
  # --------------------------------------------------
  # This script is designed to be run under DJB's
  # daemontools package.
  #
  #  ChangeLog
  #  ---------
  #
  #  09/25/03 - JDG
  #  --------------
  #  - Changed clamd user to qscand in compliance with
  #    the change to qmail-scanner-1.20rc3
  #
  #  09/10/03 - JDG
  #  --------------
  #  - Created
  # --------------------------------------------------
  # Copyright (C) 2003 WingNET Internet Services
  # Contact: Jesse D. Guardiani (jesse at wingnet dot net)
  # --------------------------------------------------

  lockfile="/tmp/clamd"   # Location of clamd lock file
  path_to_clamd="/usr/local/sbin/clamd"
                          # Location of the clamd binary
  BAD_EXIT_CODE=1         # The exit code we use to announce that something bad
  has happened

  # The following pipeline is designed to return the pid of each
  # clamd process currently running.
  get_clam_pids_pipeline=`ps -ax | grep -E "${path_to_clamd}\$" | grep -v grep
  | awk '{print $1}'`


  # --------------------------------------------------
  # Generic helper functions
  # --------------------------------------------------

  # Basic return code error message function
  die_rcode() {
  	EXIT_CODE=$1
  	ERROR_MSG=$2

  	if [ $EXIT_CODE -ne '0' ]; then
  		echo "$ERROR_MSG" 1>&amp;2
  		echo "Exiting!" 1>&amp;2
  		exit "$BAD_EXIT_CODE"
  	fi
  }


  # --------------------------------------------------
  # Main
  # --------------------------------------------------

  ps_clamd=""
  ps_clamd="$get_clam_pids_pipeline"

  if [ -n "$ps_clamd" ]; then
  	pid_count="0"
  	for pid in $ps_clamd
  	do
  		pid_count=`expr $pid_count + 1`
  	done
  	
  	die_rcode $BAD_EXIT_CODE "Error: $pid_count clamd process(es) already
  running!"

  fi

  if [ -e "$lockfile" ]; then
  	rm "$lockfile"
  	exit_code="$?"
  	die_rcode $exit_code "Error: 'rm $lockfile' call failed."
  fi

  exec /usr/local/bin/setuidgid qscand $path_to_clamd

  # --
  # END /usr/local/clamav/supervise/clamd/run file.
  # --

  Create the /usr/local/clamav/supervise/clamd/log/run file:

  #vi /usr/local/clamav/supervise/clamd/log/run

  #!/bin/sh
  exec /usr/local/bin/setuidgid qscand /usr/local/bin/multilog t /var/log/clamd
  			

Make the run files executable:

  #chmod 755 /usr/local/clamav/supervise/clamd/run


  #chmod 755 /usr/local/clamav/supervise/clamd/log/run

Now set up the log directories:

  #mkdir -p /var/log/clamd


  chown qscand /var/log/clamd

Finally, link the supervise directory into /service:

  #ln -s /usr/local/clamav/supervise/clamd /service

* Note: The clamd script will start automatically shortly after these links are
created. If you don't want it running, do the following:

  #clamdctl stop

To start clamd backup, do the following

  #clamdctl start



Chapter 4. Qmail-Scanner

Table of Contents


  1._What_Is_Qmail-Scanner?

  2._Installing_Qmail-Scanner_Prerequisites


        2.1._Maildrop

        2.2._Perl_Modules

        2.3._Mark_Simpson's_TNEF_Unpacker

        2.4._Patching_qmail


  3._Installing_Qmail-Scanner

  4._Ownership

  5._Testing


1. What Is Qmail-Scanner?

From the Qmail-Scanner website: "Qmail-Scanner is an addon that enables a qmail
email server to scan all gateway-ed email for certain characteristics (i.e. a
content scanner). It is typically used for its anti-virus protection functions,
in which case it is used in conjunction with commercial virus scanners, but
also enables a site (at a server/site level) to react to email that contains
specific strings in particular headers, or particular attachment filenames or
types (e.g. *.VBS attachments). It also can be used as an archiving tool for
auditing or backup purposes. Qmail-Scanner is integrated into the mail server
at a lower level than some other Unix-based virus scanners, resulting in better
performance. It is capable of scanning not only locally sent/received email,
but also email that crosses the server in a relay capacity."

2. Installing Qmail-Scanner Prerequisites


2.1. Maildrop

What is Maildrop:
From the maildrop web site:
"maildrop is the mail filter/mail delivery agent that's used by the Courier
Mail_Server."
You will not be using Maildrop or the Courier Mail Server for this
installation. However, Qmail-Scanner requires reformmime, which is included in
Maildrop. This is the only reason Maildrop is mentioned in this HOWTO.
Download and unpack the latest version of Maildrop. Please read the INSTALL
file included in the tar ball.

  #./configure


  #make


  #make install-strip


  #make install-man


2.2. Perl Modules

Time::HiRes Perl module:
From the README file in the tar ball:
Time::HiRes module: High resolution time, sleep, and alarm. "Implement usleep,
ualarm, and gettimeofday for Perl, as well as wrappers to implement time,
sleep, and alarm that know about non-integral seconds."
DB_File Perl module:
From the README file in the tar ball:
"DB_File is a module which allows Perl programs to make use of the facilities
provided by Berkeley DB version 1. (DB_File can be built version 2, 3 or 4 of
Berkeley DB, but it will only support the 1.x features),"
Download Time::HiRes and DB_File Perl Modules. The modules can be obtained at
www.cpan.org (See Appendix C). There is a HOWTO there as well that will explain
the installation procedure of Perl modules. Once again, please read the
instructions included in the tar balls and review the README information before
installing.

2.3. Mark Simpson's TNEF Unpacker

What is TNEF Unpacker:
This utility unpacks ms-tnef type MIME attachments. For a better explanation of
MIME type attachments, please review http://www.ietf.org/rfc/
rfc1521.txt?number=1521 .
Download the package, and uncompress the tar ball. As with the Maildrop
install, you should read the INSTALL file included in the tar ball.

  #./configure


  #./make check


  #./make install


2.4. Patching qmail

If you have not already done so, please install Bruce Guenter?s QMAILQUEUE
patch.
To patch qmail, download the patch to your qmail source directory.

  #patch -p1<qmailqueue.patch


  #./make setup check


3. Installing Qmail-Scanner

We are now ready to install Qmail-Scanner. Download the latest source of Qmail-
Scanner. As of the writing of this HOWTO, it is 1.20.
Create a user for Qmail-Scanner to run as.

  #groupadd qscand


  #useradd qscand -g qscand -c "qmail scanner" -s /nonexistent

Unpack the tar ball and change to the Qmail-Scanner directory.

  #tar -zxvf qmail-scanner-1.20.tar.gz


  #cd qmail-scanner-1.20

Run Configure to autodetect what software is installed on your system. Review
the output to make sure it is correct. It should look similar to this:

  #./configure

  This script will search your system for the virus scanners it knows
  about, and will ensure that all external programs
  qmail-scanner-queue.pl uses are explicitly pathed for performance
  reasons.

  It will then generate qmail-scanner-queue.pl - it is up to you to install it
  correctly.

  Continue? ([Y]/N) <PRESS ENTER>

  Found tnef on your system! That means we'll be able to decode stupid
  M$ attachments :-)


  The following binaries and scanners were found on your system:

  mimeunpacker=/usr/local/bin/reformime
  unzip=/usr/bin/unzip
  tnef=/usr/local/bin/tnef

  Content/Virus Scanners installed on your System

  clamuko=/usr/local/bin/clamdscan (which means clamscan won't be used as
  clamdscan is better)

  Qmail-Scanner details.

  log-details=0
  fix-mime=1
  debug=1
  notify=sender,admin
  redundant-scanning=no
  virus-admin=root@mail  --substitute you domain here
  local-domains='mail' --substitute your domain here
  silent-
  viruses='klez','bugbear','hybris','yaha','braid','nimda','tanatos','sobig','winevar','palyh','fizzer','gibe','
  cailont','lovelorn','swen','dumaru','sober','hawaii','holar-i'
  scanners="clamuko_scanner"

  If that looks correct, I will now generate qmail-scanner-queue.pl
  for your system...
  Continue? ([Y]/N)<PRESS ENTER>

  			

Now type:

  # ./configure ?install

This installs qmail-scanner-queue.pl and creates the necessary directory
structures. You should see similar messages as before. Once again, read the
output of the script to make sure everything is correct. If it is press ENTER
to install Qmail-scanner.
If qmail has been installed successfully, qmail-scanner-queue.pl should now be
installed. You should see qmail-scanner-queue.pl in /var/qmail/bin.

  #ls /var/qmail/bin


  /var/qmail/bin/qmail-scanner-queue.pl

If you do not see qmail-scanner-queue.pl in /var/qmail/bin, then execute the
configure script again. Please pay attention to the output of the script and
verify that all of the settings are correct. You can also visit the Qmail-
scanner mail-archives at http://lists.sourceforge.net/mailman/listinfo/qmail-
scanner-general .

4. Ownership

In order for Qmail-Scanner to be able to use ClamAV, some of the ClamAV
ownerships must be changed. If you recall, we made a clamav user to run ClamAV,
and then changed the permissions so only the clamav user could run it. Now we
need to provide the qscand user privledges to use ClamAV First, change the
ownership of the clamd supervise directories.

  #chown -R qscand /usr/local/clamav/supervise

Now change the ownership of the ClamAV log file:

  #chown -R qscand /var/log/clamd


5. Testing

Now test Qmail-Scanner:

  #./contrib./test_instaltion.sh -doit


  Sending standard test message - no viruses...done!


  Sending eicar test virus - should be caught by perlscanner module...
  				done!


  Sending eicar test virus with altered filename - should only be caught
  				by commercial anti-virus modules (if you have any)...


  Sending bad spam message for anti-spam testing - In case you are using
  				SpamAssassin... Done!

Now check the e-mail for your postmaster alias account.
You should now have 4 email messages in your postmaster?s mailbox
If you do not have the 4 messages in the postmaster's mailbox, then: Verify
that you are checking the proper mailbox.
Re-execute the configure script for qmail-scanner-queue.pl. Verify that the
'virus-admin' from the script output is the same as your qmail postmaster
alias.
Check qmail to see if the messages are in the queue. If they are try issuing a
'qmailctl' flush command to force delivery.
If all else fails check the Qmail-Scanner mailing list archives at http://
lists.sourceforge.net/mailman/listinfo/qmail-scanner-general.


Chapter 5. Configuring qmail to Use qmail-scanner-queue.pl

Table of Contents


  1._Changing_Your_Tcp_Rules

  2._Increasing_Your_Softlimit


1. Changing Your Tcp Rules

Once everything is installed, configured, and successfully tested, configure
qmail to utilize Qmail-Scanner and ClamAV. If you have followed the
instructions found in Dave Sills Life With qmail (see Appendix A: Reading
Resources), you should have a tcp.smtp file in your /etc directory. You must
edit tcp.smtp file to include the QMAILQUEUE variable.

#vi /etc/tcp.smtp

127.:allow,RELAYCLIENT="",QMAILQUEUE="/var/qmail/bin/qmail-queue"
10.:allow,RELAYCLIENT="",QMAILQUEUE="/var/qmail/bin/qmail-scanner-queue.pl"
:allow.QMAILQUEUE="/var/qmail/bin/qmail-scanner-queue.pl"
			
As you can see, we use qmail-queue for all local deliveries by setting the
QMAILQUEUE variable to be the original qmail-queue. We then changed the local
subnet mail deliveries to use qmail-scanner-queue.pl. This causes all local
subnet SMTP traffic to be scanned by Qmail-Scanner and ClamAV. The last line of
this file scans all inbound emails.
After adding the QMAILQUEUE variables, you must rebuild the cdb file for Qmail.

  #qmailctl cdb


2. Increasing Your Softlimit

If you try to send an email message, you will most likely receive an error from
your client. The error message will say something that includes this:

  451 qq temporary problem (#4.3.0)

If you followed Life with qmail, you then have a memory limit set in the /var/
qmail/supervise/qmail-smtpd/run file. Look for the line that contains
softlimit. It should look similar to this:

  exec /usr/local/bin/softlimit -m 2000000 \

This example sets the memory limit for qmail-smtpd to 2M. After all of your
changes qmail-smtpd is now running the entire Perl interpreter, and ClamAV. 2M
will never be enough.
Each system is different, and has different requirements. It will take some
experimenting on your part to find the correct value for your system's
softlimit. Do not set softlimit to some high value! You are asking for trouble
if you do this. To find the minimal value for your system, I recommend the
following steps:

* Increase softlimit by 1M
* #qmailctl restart
* Send a message
* Repeat until you can successfully send an email

Once you have found the minimum, I recommend increasing that by 1.5M, just for
times that your email server has a heavy load.
After that just create a daily cronjob that runs /var/qmail/bin/qmail-scan-
queue.pl -z to cleanup any dropped SMTP sessions that may be lying around in /
var/spool/qmailscan.


Chapter 6. Conclusion

After following the instructions in this HOWTO, now you can feel confident
about your email messages being more secure. By implementing Qmail-Scanner and
clamav, you have successfully added another layer of security to your email
system and overall anti-virus protection. Of course, there is no such thing as
100% secure email messages. Nor will this installation replace sound anti-virus
practices, but it should make those practices a little easier to implement and
manage.


Appendix A. Recommended Reading and Other Resources


Life with qmail written by Dave Sills http://www.lifewithqmail.org
qmail FAQ Written by D.J. Bernstein http://cr.yp.to/qmail/faq
SMTP: Simple Mail Transfer Protocol written by Dan Bernstein http://cr.yp.to/
smtp.html
Daemontools FAQ written by D.J. Bernstein http://cr.yp.to/daemontools/faq
ClamAV FAQ http://www.clamav.net/faq.html#pagestart
ClamAV User Manual Written by Thomasz Kojm http://www.clamav.net/doc
Qmail-Scanner: Content Scanner for qmail written by Jason Haar http://qmail-
scanner.sourceforge.net
Qmail-Scanner FAQ http://qmail-scanner.sourceforge.net/FAQ.php
Clamd+daemontools howto written by Jesse D. Guardiani http://
clamav.elektrapro.com/doc/clamd_supervised/clamd-daemontools-guide.txt
qmail mailing list archive http://www-archive.ornl.gov:8000/
Qmail-Scanner list archive http://sourceforge.net/mailarchive/
forum.php?forum=qmail-scanner-general
ClamAV users list archive http://news.gmane.org/
gmane.comp.security.virus.clamav.user
ClamAV Virus DB list archive http://news.gmane.org/
gmane.comp.security.virus.clamav.virusdb
Maildrop http://www.flounder.net/~mrsam/maildrop/
Perl module installation HOWTO http://www.cpan.org/modules/INSTALL.html
Mime type RFC http://www.ietf.org/rfc/rfc1521.txt?number=1521



Appendix B. Scripts

These are the scripts contained in this HOWTO. They were created by Jesse D.
Guardiani, and can be found in his clamd+daemontools HOWTO.
Clamdctl

  #!/bin/sh

  # For Red Hat chkconfig
  # chkconfig: - 80 30
  # description: the ClamAV clamd daemon

  PATH=/usr/local/clamav/bin:/bin:/usr/bin:/usr/local/bin:/usr/local/sbin
  export PATH

  case "$1" in
    start)
      echo "Starting clamd"
      if svok /service/clamd ; then
        svc -u /service/clamd
      else
        echo clamd supervise not running
      fi
      if [ -d /var/lock/subsys ]; then
        touch /var/lock/subsys/clamd
      fi
      ;;
    stop)
      echo "Stopping clamd..."
      echo "  clamd"
      svc -d /service/clamd
      if [ -f /var/lock/subsys/clamd ]; then
        rm /var/lock/subsys/clamd
      fi
      ;;
    stat)
      svstat /service/clamd
      svstat /service/clamd/log
      ;;
    restart)
      echo "Restarting clamd:"
      echo "* Stopping clamd."
      svc -d /service/clamd
      echo "* Sending clamd SIGTERM and restarting."
      svc -t /service/clamd
      echo "* Restarting clamd."
      svc -u /service/clamd
      ;;
    hup)
      echo "Sending HUP signal to clamd."
      svc -h /service/clamd
      ;;
    help)
      cat <<HELP
     stop -- stops clamd service (smtp connections refused, nothing goes out)
    start -- starts clamd service (smtp connection accepted, mail can go out)
     stat -- displays status of clamd service
  restart -- stops and restarts the clamd service
      hup -- same as reload
  HELP
      ;;
    *)
      echo "Usage: $0 {start|stop|stat|restart|hup|help}"
      exit 1
      ;;
  esac

  exit 0

/usr/local/clamav/supervise/clamd/run

  vi /usr/local/clamav/supervise/clamd/run

  #!/bin/sh
  #
  # --------------------------------------------------
  # run
  #
  # Purpose     - Start the clamd daemon/service.
  #
  # Author      - Jesse D. Guardiani
  # Created     - 09/10/03
  # Modified    - 09/25/03
  # --------------------------------------------------
  # This script is designed to be run under DJB's
  # daemontools package.
  #
  #  ChangeLog
  #  ---------
  #
  #  09/25/03 - JDG
  #  --------------
  #  - Changed clamd user to qscand in compliance with
  #    the change to qmail-scanner-1.20rc3
  #
  #  09/10/03 - JDG
  #  --------------
  #  - Created
  # --------------------------------------------------
  # Copyright (C) 2003 WingNET Internet Services
  # Contact: Jesse D. Guardiani (jesse at wingnet dot net)
  # --------------------------------------------------

  lockfile="/tmp/clamd"   # Location of clamd lock file
  path_to_clamd="/usr/local/sbin/clamd"
                          # Location of the clamd binary
  BAD_EXIT_CODE=1         # The exit code we use to announce that something bad
  has happened

  # The following pipeline is designed to return the pid of each
  # clamd process currently running.
  get_clam_pids_pipeline=`ps -ax | grep -E "${path_to_clamd}\$" | grep -v grep
  | awk '{print $1}'`


  # --------------------------------------------------
  # Generic helper functions
  # --------------------------------------------------

  # Basic return code error message function
  die_rcode() {
  	EXIT_CODE=$1
  	ERROR_MSG=$2

  	if [ $EXIT_CODE -ne '0' ]; then
  		echo "$ERROR_MSG" 1>&amp;2
  		echo "Exiting!" 1>&amp;2
  		exit "$BAD_EXIT_CODE"
  	fi
  }


  # --------------------------------------------------
  # Main
  # --------------------------------------------------

  ps_clamd=""
  ps_clamd="$get_clam_pids_pipeline"

  if [ -n "$ps_clamd" ]; then
  	pid_count="0"
  	for pid in $ps_clamd
  	do
  		pid_count=`expr $pid_count + 1`
  	done
  	
  	die_rcode $BAD_EXIT_CODE "Error: $pid_count clamd process(es) already
  running!"

  fi

  if [ -e "$lockfile" ]; then
  	rm "$lockfile"
  	exit_code="$?"
  	die_rcode $exit_code "Error: 'rm $lockfile' call failed."
  fi

  exec /usr/local/bin/setuidgid qscand $path_to_clamd

  # --
  # END /usr/local/clamav/supervise/clamd/run file.
  # --

  Create the /usr/local/clamav/supervise/clamd/log/run file:

  #vi /usr/local/clamav/supervise/clamd/log/run

  #!/bin/sh
  exec /usr/local/bin/setuidgid qscand /usr/local/bin/multilog t /var/log/clamd
  			

/usr/local/clamav/supervise/clamd/log/run

  #!/bin/sh
  exec /usr/local/bin/setuidgid qscand /usr/local/bin/multilog t /var/log/clamd
  			



Appendix C. Software


qmail- http://www.qmail.org/netqmail-1.05.tar.gz
Daemontools- ftp://cr.yp.to/daemontools/daemontools-0.76.tar.gz
ClamAV- http://prodownloads.sourceforge.net/clamav/clamav-0.65.tar.gz
QMAILQUEUE Patch- http://www.qmail.org/top.html#qmailqueue
MailDrop- http://download.sourceforge.net/courier
Time::HiRes - http://search.cpan.org/search?module=Time::HiRes
DB_File- http://search.cpan.org/search?module=DB_File
TNEF unpacker- http://sourcforge.net/projects/tnef
Qmail-Scanner- http://prodownloads.sourceforge.net/qmail-scanner/qmail-scanner-
1.20.tgz?download
MIME type RFC- http://www.ietf.org/rfc/rfc1521.txt?number=1521



Appendix D. GNU Free Documentation License


Version 1.2, November 2002

Table of Contents


  1._PREAMBLE

  2._APPLICABILITY_AND_DEFINITIONS

  3._VERBATIM_COPYING

  4._COPYING_IN_QUANTITY

  5._MODIFICATIONS

  6._COMBINING_DOCUMENTS

  7._COLLECTIONS_OF_DOCUMENTS

  8._AGGREGATION_WITH_INDEPENDENT_WORKS

  9._TRANSLATION

  10._TERMINATION

  11._FUTURE_REVISIONS_OF_THIS_LICENSE

  12._ADDENDUM:_How_to_use_this_License_for_your_documents


     FSF Copyright note
     Copyright (C) 2000,2001,2002 Free Software Foundation, Inc. 59 Temple
     Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to
     copy and distribute verbatim copies of this license document, but
     changing it is not allowed.


1. PREAMBLE

The purpose of this License is to make a manual, textbook, or other functional
and useful document "free" in the sense of freedom: to assure everyone the
effective freedom to copy and redistribute it, with or without modifying it,
either commercially or noncommercially. Secondarily, this License preserves for
the author and publisher a way to get credit for their work, while not being
considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative works of the
document must themselves be free in the same sense. It complements the GNU
General Public License, which is a copyleft license designed for free software.
We have designed this License in order to use it for manuals for free software,
because free software needs free documentation: a free program should come with
manuals providing the same freedoms that the software does. But this License is
not limited to software manuals; it can be used for any textual work,
regardless of subject matter or whether it is published as a printed book. We
recommend this License principally for works whose purpose is instruction or
reference.

2. APPLICABILITY AND DEFINITIONS

This License applies to any manual or other work, in any medium, that contains
a notice placed by the copyright holder saying it can be distributed under the
terms of this License. Such a notice grants a world-wide, royalty-free license,
unlimited in duration, to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member of the public
is a licensee, and is addressed as "you". You accept the license if you copy,
modify or distribute the work in a way requiring permission under copyright
law.
A "Modified Version" of the Document means any work containing the Document or
a portion of it, either copied verbatim, or with modifications and/or
translated into another language.
A "Secondary Section" is a named appendix or a front-matter section of the
Document that deals exclusively with the relationship of the publishers or
authors of the Document to the Document's overall subject (or to related
matters) and contains nothing that could fall directly within that overall
subject. (Thus, if the Document is in part a textbook of mathematics, a
Secondary Section may not explain any mathematics.) The relationship could be a
matter of historical connection with the subject or with related matters, or of
legal, commercial, philosophical, ethical or political position regarding them.
The "Invariant Sections" are certain Secondary Sections whose titles are
designated, as being those of Invariant Sections, in the notice that says that
the Document is released under this License. If a section does not fit the
above definition of Secondary then it is not allowed to be designated as
Invariant. The Document may contain zero Invariant Sections. If the Document
does not identify any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are listed, as Front-
Cover Texts or Back-Cover Texts, in the notice that says that the Document is
released under this License. A Front-Cover Text may be at most 5 words, and a
Back-Cover Text may be at most 25 words.
A "Transparent" copy of the Document means a machine-readable copy, represented
in a format whose specification is available to the general public, that is
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formatters or for automatic translation to a variety of formats suitable for
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whose markup, or absence of markup, has been arranged to thwart or discourage
subsequent modification by readers is not Transparent. An image format is not
Transparent if used for any substantial amount of text. A copy that is not
"Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain ASCII without
markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly
available DTD, and standard-conforming simple HTML, PostScript or PDF designed
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and JPG. Opaque formats include proprietary formats that can be read and edited
only by proprietary word processors, SGML or XML for which the DTD and/or
processing tools are not generally available, and the machine-generated HTML,
PostScript or PDF produced by some word processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself, plus such
following pages as are needed to hold, legibly, the material this License
requires to appear in the title page. For works in formats which do not have
any title page as such, "Title Page" means the text near the most prominent
appearance of the work's title, preceding the beginning of the body of the
text.
A section "Entitled XYZ" means a named subunit of the Document whose title
either is precisely XYZ or contains XYZ in parentheses following text that
translates XYZ in another language. (Here XYZ stands for a specific section
name mentioned below, such as "Acknowledgements", "Dedications",
"Endorsements", or "History".) To "Preserve the Title" of such a section when
you modify the Document means that it remains a section "Entitled XYZ"
according to this definition.
The Document may include Warranty Disclaimers next to the notice which states
that this License applies to the Document. These Warranty Disclaimers are
considered to be included by reference in this License, but only as regards
disclaiming warranties: any other implication that these Warranty Disclaimers
may have is void and has no effect on the meaning of this License.

3. VERBATIM COPYING

You may copy and distribute the Document in any medium, either commercially or
noncommercially, provided that this License, the copyright notices, and the
license notice saying this License applies to the Document are reproduced in
all copies, and that you add no other conditions whatsoever to those of this
License. You may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However, you may
accept compensation in exchange for copies. If you distribute a large enough
number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may
publicly display copies.

4. COPYING IN QUANTITY

If you publish printed copies (or copies in media that commonly have printed
covers) of the Document, numbering more than 100, and the Document's license
notice requires Cover Texts, you must enclose the copies in covers that carry,
clearly and legibly, all these Cover Texts: Front-Cover Texts on the front
cover, and Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The front cover must
present the full title with all words of the title equally prominent and
visible. You may add other material on the covers in addition. Copying with
changes limited to the covers, as long as they preserve the title of the
Document and satisfy these conditions, can be treated as verbatim copying in
other respects.
If the required texts for either cover are too voluminous to fit legibly, you
should put the first ones listed (as many as fit reasonably) on the actual
cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than
100, you must either include a machine-readable Transparent copy along with
each Opaque copy, or state in or with each Opaque copy a computer-network
location from which the general network-using public has access to download
using public-standard network protocols a complete Transparent copy of the
Document, free of added material. If you use the latter option, you must take
reasonably prudent steps, when you begin distribution of Opaque copies in
quantity, to ensure that this Transparent copy will remain thus accessible at
the stated location until at least one year after the last time you distribute
an Opaque copy (directly or through your agents or retailers) of that edition
to the public.
It is requested, but not required, that you contact the authors of the Document
well before redistributing any large number of copies, to give them a chance to
provide you with an updated version of the Document.

5. MODIFICATIONS

You may copy and distribute a Modified Version of the Document under the
conditions of sections 2 and 3 above, provided that you release the Modified
Version under precisely this License, with the Modified Version filling the
role of the Document, thus licensing distribution and modification of the
Modified Version to whoever possesses a copy of it. In addition, you must do
these things in the Modified Version:
GNU FDL Modification Conditions

  a. Use in the Title Page (and on the covers, if any) a title distinct from
     that of the Document, and from those of previous versions (which should,
     if there were any, be listed in the History section of the Document). You
     may use the same title as a previous version if the original publisher of
     that version gives permission.
  b. List on the Title Page, as authors, one or more persons or entities
     responsible for authorship of the modifications in the Modified Version,
     together with at least five of the principal authors of the Document (all
     of its principal authors, if it has fewer than five), unless they release
     you from this requirement.
  c. State on the Title page the name of the publisher of the Modified Version,
     as the publisher.
  d. Preserve all the copyright notices of the Document.
  e. Add an appropriate copyright notice for your modifications adjacent to the
     other copyright notices.
  f. Include, immediately after the copyright notices, a license notice giving
     the public permission to use the Modified Version under the terms of this
     License, in the form shown in the Addendum below.
  g. Preserve in that license notice the full lists of Invariant Sections and
     required Cover Texts given in the Document's license notice.
  h. Include an unaltered copy of this License.
  i. Preserve the section Entitled "History", Preserve its Title, and add to it
     an item stating at least the title, year, new authors, and publisher of
     the Modified Version as given on the Title Page. If there is no section
     Entitled "History" in the Document, create one stating the title, year,
     authors, and publisher of the Document as given on its Title Page, then
     add an item describing the Modified Version as stated in the previous
     sentence.
  j. Preserve the network location, if any, given in the Document for public
     access to a Transparent copy of the Document, and likewise the network
     locations given in the Document for previous versions it was based on.
     These may be placed in the "History" section. You may omit a network
     location for a work that was published at least four years before the
     Document itself, or if the original publisher of the version it refers to
     gives permission.
  k. For any section Entitled "Acknowledgements" or "Dedications", Preserve the
     Title of the section, and preserve in the section all the substance and
     tone of each of the contributor acknowledgements and/or dedications given
     therein.
  l. Preserve all the Invariant Sections of the Document, unaltered in their
     text and in their titles. Section numbers or the equivalent are not
     considered part of the section titles.
  m. Delete any section Entitled "Endorsements". Such a section may not be
     included in the Modified Version.
  n. Do not retitle any existing section to be Entitled "Endorsements" or to
     conflict in title with any Invariant Section.
  o. Preserve any Warranty Disclaimers.

If the Modified Version includes new front-matter sections or appendices that
qualify as Secondary Sections and contain no material copied from the Document,
you may at your option designate some or all of these sections as invariant. To
do this, add their titles to the list of Invariant Sections in the Modified
Version's license notice. These titles must be distinct from any other section
titles.
You may add a section Entitled "Endorsements", provided it contains nothing but
endorsements of your Modified Version by various parties--for example,
statements of peer review or that the text has been approved by an organization
as the authoritative definition of a standard.
You may add a passage of up to five words as a Front-Cover Text, and a passage
of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts
in the Modified Version. Only one passage of Front-Cover Text and one of Back-
Cover Text may be added by (or through arrangements made by) any one entity. If
the Document already includes a cover text for the same cover, previously added
by you or by arrangement made by the same entity you are acting on behalf of,
you may not add another; but you may replace the old one, on explicit
permission from the previous publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this License give
permission to use their names for publicity for or to assert or imply
endorsement of any Modified Version.

6. COMBINING DOCUMENTS

You may combine the Document with other documents released under this License,
under the terms defined in section_4 above for modified versions, provided that
you include in the combination all of the Invariant Sections of all of the
original documents, unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all their Warranty
Disclaimers.
The combined work need only contain one copy of this License, and multiple
identical Invariant Sections may be replaced with a single copy. If there are
multiple Invariant Sections with the same name but different contents, make the
title of each such section unique by adding at the end of it, in parentheses,
the name of the original author or publisher of that section if known, or else
a unique number. Make the same adjustment to the section titles in the list of
Invariant Sections in the license notice of the combined work.
In the combination, you must combine any sections Entitled "History" in the
various original documents, forming one section Entitled "History"; likewise
combine any sections Entitled "Acknowledgements", and any sections Entitled
"Dedications". You must delete all sections Entitled "Endorsements".

7. COLLECTIONS OF DOCUMENTS

You may make a collection consisting of the Document and other documents
released under this License, and replace the individual copies of this License
in the various documents with a single copy that is included in the collection,
provided that you follow the rules of this License for verbatim copying of each
of the documents in all other respects.
You may extract a single document from such a collection, and distribute it
individually under this License, provided you insert a copy of this License
into the extracted document, and follow this License in all other respects
regarding verbatim copying of that document.

8. AGGREGATION WITH INDEPENDENT WORKS

A compilation of the Document or its derivatives with other separate and
independent documents or works, in or on a volume of a storage or distribution
medium, is called an "aggregate" if the copyright resulting from the
compilation is not used to limit the legal rights of the compilation's users
beyond what the individual works permit. When the Document is included in an
aggregate, this License does not apply to the other works in the aggregate
which are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these copies of the
Document, then if the Document is less than one half of the entire aggregate,
the Document's Cover Texts may be placed on covers that bracket the Document
within the aggregate, or the electronic equivalent of covers if the Document is
in electronic form. Otherwise they must appear on printed covers that bracket
the whole aggregate.

9. TRANSLATION

Translation is considered a kind of modification, so you may distribute
translations of the Document under the terms of section 4. Replacing Invariant
Sections with translations requires special permission from their copyright
holders, but you may include translations of some or all Invariant Sections in
addition to the original versions of these Invariant Sections. You may include
a translation of this License, and all the license notices in the Document, and
any Warranty Disclaimers, provided that you also include the original English
version of this License and the original versions of those notices and
disclaimers. In case of a disagreement between the translation and the original
version of this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled "Acknowledgements", "Dedications", or
"History", the requirement (section 4) to Preserve its Title (section 1) will
typically require changing the actual title.

10. TERMINATION

You may not copy, modify, sublicense, or distribute the Document except as
expressly provided for under this License. Any other attempt to copy, modify,
sublicense or distribute the Document is void, and will automatically terminate
your rights under this License. However, parties who have received copies, or
rights, from you under this License will not have their licenses terminated so
long as such parties remain in full compliance.

11. FUTURE REVISIONS OF THIS LICENSE

The Free Software Foundation may publish new, revised versions of the GNU Free
Documentation License from time to time. Such new versions will be similar in
spirit to the present version, but may differ in detail to address new problems
or concerns. See http://www.gnu.org/copyleft/.
Each version of the License is given a distinguishing version number. If the
Document specifies that a particular numbered version of this License "or any
later version" applies to it, you have the option of following the terms and
conditions either of that specified version or of any later version that has
been published (not as a draft) by the Free Software Foundation. If the
Document does not specify a version number of this License, you may choose any
version ever published (not as a draft) by the Free Software Foundation.

12. ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the
License in the document and put the following copyright and license notices
just after the title page:

     Sample Invariant Sections list
     Copyright (c) YEAR YOUR NAME. Permission is granted to copy,
     distribute and/or modify this document under the terms of the GNU
     Free Documentation License, Version 1.2 or any later version
     published by the Free Software Foundation; with no Invariant
     Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of
     the license is included in the section entitled "GNU Free
     Documentation License".

If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace
the "with...Texts." line with this:

     Sample Invariant Sections list
     with the Invariant Sections being LIST THEIR TITLES, with the Front-
     Cover Texts being LIST, and with the Back-Cover Texts being LIST.

If you have Invariant Sections without Cover Texts, or some other combination
of the three, merge those two alternatives to suit the situation.
If your document contains nontrivial examples of program code, we recommend
releasing these examples in parallel under your choice of free software
license, such as the GNU General Public License, to permit their use in free
software.