Campbell, Calif. -- Sourcefire, a Maryland-based developer of open source intrusion detection technology, said that its board of directors has rejected an unsolicited takeover bid by Campbell-based Barracuda Networks, a maker of email and web security appliances. Barracuda late Thursday revealed an offer to acquire the company for $7.50 a share, or about $187.5 million. "We hope to work together with Sourcefire and its board of directors to negotiate a mutually beneficial agreement for our respective stakeholders," said Dean Drako, Barracuda's president and CEO. In a letter to Sourcefire CEO Wayne Jackson and the company’s board, Drako said that a recent decline in the price of the Maryland firm's stock -- which closed on Thursday about $10 off its 52-week high -- reflects "execution challenges" faced by its management, as well as its "inaction" in dealing with looming litigation from Trend Micro. "Barracuda Networks is uniquely positioned to address and remedy both of these conditions," said Drako. In response, however, Sourcefire said that the offer "substantially undervalues" the company.