Security appliance vendor Barracuda Networks is looking to buy Sourcefire, makers of the open-source Snort and ClamAV security software.

Barracuda has bid for intrusion detection company, Sourcefire. Barracuda is willing to pay $7.50 per share, a 13 percent premium on the company's current stock price, but about half what shares Sourcefire fetched a year ago.

"Barracuda Networks is uniquely positioned to address the challenges that have impacted the company's performance and stock price," Barracuda said in a statement.

Although Sourcefire is best known for its intrusion detection software, the company bought the ClamAV open source anti-virus project last August, and is now working on ways to commercialise this code.

That's an area where Barracuda believes it can help out. ClamAV is included in Barracuda's appliance products.

The open-source software has been at the source of a high-profile legal dispute between Barracuda and competitor Trend Micro, which claims that ClamAV violates one of its patents.

Because it is already fighting a lawsuit with Trend Micro, Barracuda feels it is already addressing what could turn into a legal problem for Sourcefire, Barracuda president and CEO Dean Drako said in a letter to Sourcefire's board of directors, which Barracuda made public Thursday.

"We also feel that the company's inaction in dealing with the looming threat of litigation from Trend Micro has had an effect on the stock price," he wrote.

Sourcefire representatives could not be reached immediately for comment, but the fact that Barracuda felt compelled to take its offer public suggests that it was not well-received by Sourcefire's board of directors.