(FORTUNE Magazine) – Cupertino, Calif. Founded 1998

During the war in Iraq, the U.S. needed to give its allies temporary access to the computer network that coordinated battlefield activity--without also making the system open to Saddam. So it turned to Securify, a company that doesn't just keep bad guys out of networks, but makes sure those inside the firewall are following the rules. Securify's software acts like a digital security guard: It checks what's on the network and analyzes traffic for abnormalities. It also alerts IT security officials when, say, a consultant or an employee snoops where he shouldn't be or when a former employee uses still-active passwords to enter the company's systems. For one customer, which Securify won't name, it found a worker running an electronic music store off the corporate network.

In the two years that Securify has been selling its software, it's put together a blue-chip list of corporate and government customers that have signed contracts totaling some $12 million. New CEO Dave Peterschmidt, the 56-year-old former CEO of Inktomi and COO of Sybase, sees a huge new market. As companies try to allow more and more outsiders into their networks--a process that's easier and more efficient than faxing or express-mailing documents back and forth--they also create massive security holes. Securify thinks it has the plug. --Fred Vogelstein