In an earlier HowTo 'Deploying A Content Filtering Proxy Server To Distribute Controlled Internet Access With SafeSquid', I had explained the procedure for installing Content Filtering Proxy - SafeSquid. In this HowTo, I will explain how you can secure your network from virus and other malware, by installing ClamAV and integrating it with SafeSquid, to scan all in-coming content for virus, and block all infected content at the HTTP Gateway, even before it enters your network.

Virus Security In SafeSquid

SafeSquid has built-in connectivity to various daemon based anti virus software like ClamAV, Sophos, Avast, F-Prot, NOD32 and Kaspersky. It also has a universal ICAP (Internet Content Adaptation Protocol) client that can be used to connect to ICAP based security software like Dr.Web ICAP, Kaspersky Antivirus for Proxy Server, Trend Micro InterScan Web Security and Symantec Scan Engine.

You can even use multiple anti virus software with SafeSquid to simultaneously scan in-coming content. This does not cause any significant latency, since SafeSquid has a multi-threaded architecture. 

Installing ClamAV And Integrating With SafeSquid

Change directory to /usr/local/src:

cd /usr/local/src

Download ClamAV: 

wget -nd http://freshmeat.net/redir/clamav/29355/url_tgz/clamav-0.91.tar.gz

Decompress the tar file using command:

tar -xvzf clamav-0.91.tar.gz

Add user 'clamav':

useradd clamav

Change to 'clamav-0.91' directory:

cd clamav-0.91/

Install clamav:

./configure && make && make install

After the installation is complete, copy "contrib/init/RedHat/clamd" file to "/etc/init.d/":

cp contrib/init/RedHat/clamd /etc/init.d/clamd

Configure clamav to auto-run on startup:

chkconfig --add clamd

Edit clamd.conf and comment the line 'EXAMPLE':

vi /usr/local/etc/clamd.conf

EXAMPLE => # EXAMPLE

Edit freshclamav.conf and comment the line 'EXAMPLE':

vi /usr/local/etc/freshclamd.conf

EXAMPLE => # EXAMPLE

Run freshclam to update database:

freshclam -v

The output should be similar to -

Current working dir is /usr/local/share/clamav
Max retries == 3
ClamAV update process started at Mon Mar 10 03:11:09 2008
Querying current.cvd.clamav.net
TTL: 208
Software version from DNS: 0.92.1
DON'T PANIC! Read http://www.clamav.net/support/faq
main.cvd version from DNS: 45
main.inc is up to date (version: 45, sigs: 169676, f-level: 21, builder: sven)
daily.cvd version from DNS: 6189
Downloading daily.cvd [10%...}
daily.cvd is up to date (version: 6190, sigs: 59083, f-level: 26, builder: ccordes)

Add a cron job for daily auto update:

vi /etc/crontab

Add the following lines to run freshclam daily at 10 hours:

00 10 * * * root /usr/local/bin/freshclam

Start Clamav daemon:

/etc/init.d/clamd start

Check status:

/etc/init.d/clamd status

The output should be similar to -

clamd (pid 1525) is running...

So now your ClamAV daemon is up and running. The next step is to configure SafeSquid to use ClamAV daemon.

Check the socket path of ClamAV:

netstat -lnp | grep clamd

Check for this output -

'unix 2 [ ACC ] STREAM LISTENING 29235 5643/clamd /tmp/clamd.socket'

So the socket path is /tmp/clamd.socket.

Open the SafeSquid Web Interface, click on 'Config' in the main menu, select 'Client for ClamAV Antivirus' and click on 'Submit' to open ClamAV section.
Normally you will find this section already configured with a default rule, but disabled (Enabled = No). You only have to enable this section ( Enable = Yes)

It should have the following setting. If not, then edit accordingly:

'clamav section'
Enabled = Yes
ClamAV hostname or socket path = /tmp/clamd.socket

'clamav sub-section'
Enabled = Yes
Profiles = antivirus (this profile is defined in 'Profiles' section, which is generated by another profile 'application-filter', which defines the type of files to be scanned)

ClamAV Section In SafeSquid Web Interface

To test your installation, visit http://eicar.org/anti_virus_test_file.htm and scroll down to "Download area using the standard protocol http". Click on the files listed under this section. You should get a message -

ClamAV detected: Eicar-Test-Signature
in
http://www.eicar.org:80/download/eicar.com

EICAR Antivirus Test Page

Congratulations!
You have just set up the first layer of security from virus and malware for your network.

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