Clam AntiVirus

Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX, designed especially for e-mail scanning on mail gateways. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. The core of the package is an anti-virus engine available in a form of shared library.

How To Automatically Scan Uploaded Files For Viruses With php-clamavlib | HowtoForge – Linux Howtos and Tutorials

This guide describes how you can automatically scan files uploaded by users through a web form on your server using PHP and ClamAV. That way you can make sure that your upload form will not be abused to distribute malware. To glue PHP and ClamAV, we install the package php5-clamavlib/php4-clamavlib which is rather undocumented at this time. That package is available for Debian Etch and Sid and also for Ubuntu Dapper Drake and Edgy Eft, so make sure you use one of these platforms.