ClamAV/SOSDG (formerly ClamAV For Windows) is a Windows command line version of the GPL licensed anti-virus solution. It includes a set of command line tools, including a high speed scanning daemon, that can be used to scan computers for viruses, or used by mail servers or proxy servers (via command line) to clean incoming messages. The program offers free definition updates and comes with detailed (PDF) documentation. Suited for advanced users only.