How To Integrate ClamAV Into PureFTPd For Virus Scanning On CentOS 5.4

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Author: Falko Timme <ft [at] falkotimme [dot] com>
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Last edited 04/14/2010

This tutorial explains how you can integrate ClamAV into PureFTPd for virus scanning on a CentOS 5.4 system. In the end, whenever a file gets uploaded through PureFTPd, ClamAV will check the file and delete it if it is malware.

I do not issue any guarantee that this will work for you!

1 Preliminary Note

You should have a working PureFTPd setup on your CentOS 5.4 server, e.g. as shown in this tutorial: Virtual Hosting With PureFTPd And MySQL (Incl. Quota And Bandwidth Management) On CentOS 5.3 (yes, it's for CentOS 5.3, but works for CentOS 5.4 as well).

2 Installing ClamAV

ClamAV is not available in the official CentOS repositories, therefore we enable the RPMforge repository:

rpm --import http://dag.wieers.com/rpm/packages/RPM-GPG-KEY.dag.txt

cd /tmp
wget http://dag.wieers.com/rpm/packages/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm
rpm -ivh rpmforge-release-0.3.6-1.el5.rf.x86_64.rpm

Afterwards we can install ClamAV as follows:

yum install clamav clamd

Next we create the system startup links for clamd and start it:

chkconfig --levels 235 clamd on
/usr/bin/freshclam

/etc/init.d/clamd start

3 Configuring PureFTPd

First we open /etc/pure-ftpd/pure-ftpd.conf and set CallUploadScript to yes :

vi /etc/pure-ftpd/pure-ftpd.conf

[...]
# If your pure-ftpd has been compiled with pure-uploadscript support,
# this will make pure-ftpd write info about new uploads to
# /var/run/pure-ftpd.upload.pipe so pure-uploadscript can read it and
# spawn a script to handle the upload.

CallUploadScript yes
[...]

Next we create the file /etc/pure-ftpd/clamav_check.sh (which will call /usr/bin/clamdscan whenever a file is uploaded through PureFTPd)...

vi /etc/pure-ftpd/clamav_check.sh

#!/bin/sh
/usr/bin/clamdscan --remove --quiet --no-summary "$1"

... and make it executable:

chmod 755 /etc/pure-ftpd/clamav_check.sh

Now we start the pure-uploadscript program as a daemon - it will call our /etc/pure-ftpd/clamav_check.sh script whenever a file is uploaded through PureFTPd:

pure-uploadscript -B -r /etc/pure-ftpd/clamav_check.sh

Of course, you don't want to start the daemon manually each time you boot the system - therefore we open /etc/rc.local...

vi /etc/rc.local

... and add the line /usr/sbin/pure-uploadscript -B -r /etc/pure-ftpd/clamav_check.sh to it - e.g. as follows:

#!/bin/sh
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.

/usr/sbin/pure-uploadscript -B -r /etc/pure-ftpd/clamav_check.sh
touch /var/lock/subsys/local

Finally we restart PureFTPd:

/etc/init.d/pure-ftpd restart

That's it! Now whenever someone tries to upload malware to your server through PureFTPd, the "bad" file(s) will be silently deleted.

4 Links

• PureFTPD: http://www.pureftpd.org/
• ClamAV: http://www.clamav.net/
• CentOS: http://www.centos.org/