Trend Micro may have received more than it bargained for in its software patent dispute with rival Barracuda Networks. In the past few months Barracuda's cause has been taken up by free software advocates, who see Trend Micro's patent claims as a threat to the open-source ClamAV antivirus project. That's because Barracuda uses ClamAV to be able to scan for viruses at the "gateway," where a local area network connects to the Internet. Trend Micro says it owns the technology behind this -- thanks to a patent it calls the "600" patent.