Barracuda Networks is counter-suing Trend Micro for infringement of three security patents that Barracuda acquired earlier this year from IBM, the company has announced.

Trend Micro originally brought suit against Barracuda for infringement of its gateway virus scanning patent, US Patent 5,623,600, in federal district court in 2006. Trend Micro then switched tactics and filed a complaint with the International Trade Commission on November 21, 2007.

Barracuda continues to seek help from open source developers and users to beat Trend Micro's patent by finding earlier examples of the patented technique, so-called "prior art" that would invalidate the patent.

Barracuda's three new patents cover commonly used Internet security technologies. Barracuda was practicing all three without a license before acquiring them, CEO Dean Drako said in a phone interview. The terms of the sale include licensing the patents back to IBM, he adds, but he did not disclose the price paid or any other details of the sale.

The three patents are: 7,093,287, which covers firewalling connections by matching keywords in content, 7,093,294, which covers detecting zombie hosts by watching for outbound distributed denial-of-service traffic and matching it to the inbound connection that the distributed DoS perpetrator uses to control the zombie, and 7,103,913, which covers screening executables for malware by running them in a known environment and looking for hostile changes to the system.

"These are extremely broad, extremely good patents," Drako says, but he asks users not to bust them by searching for prior art. "In my heart of hearts I hope that everyone would ignore their call for prior art," he says. The difference is that I'm not out attacking the open source community."

Barracuda, however, has not made any formal commitment not to use the patents aggressively, Drako says. But the company is considering licensing the three patents for open source under terms similar to the Red Hat's patent promise. "I think we will go and do a Red Hat-like commitment [in] that we're committed to not asserting these against open source projects." he says.

Despite his new patent portfolio, Drako is still critical of the software patent system.

"I would much rather spend my time and money and energy finding ways to make the Internet safer and better than bickering over patents," he says. "The Internet has a bunch of bad stuff on it and it would be better for everyone if if were a safer place."