WASHINGTON--The National Security Agency may be known for its stealthy eavesdropping techniques, but it's going public with advice for how to train a new generation to defend against computer threats.

Representatives from the usually secretive agency appeared at a SANS Institute event here to divulge "lessons learned" from their latest cyberdefense exercise. The exercise, which took place over four days in April, pitted students from the five U.S. military academies and the Air Force's postgraduate technology school against "bad guys" at NSA headquarters.

The NSA-sponsored exercise, unlike other governmental attempts at bolstering cyberpreparedness, has been regularly taking place for six years. Friday's public presentation, however, was described as the first of its kind. (The Department of Homeland Security, the agency chiefly responsible for safeguarding federal agencies' cybersafety, wrapped up its first large-scale mock attack earlier this year, with an analysis of its results expected this summer.)

NSA representatives said they hoped the informal briefing would provide a wake-up call to all network managers, both inside and outside the government.

"Even in four days, a network can be had," said Major Thomas Augustine, the event's coordinator. "Imagine, if you will, those individuals who have a year or two to spare and are waiting to get into your networks."

During the exercise, each team received network software that had been tainted by a group of NSA representatives, and each had two weeks to find as many misconfigurations and vulnerabilities as they could. Separate groups of NSA representatives, who were unaware of the existing vulnerabilities, then went to work over the four days attempting to hack into networks. The networks were designed and built by each military team and employed the NSA-supplied software.

In hopes of simulating a real-world situation, the attackers made a point of using the most publicly known exploits during the competition. They also took advantage of common mistakes like the use of weak passwords or the same passwords on multiple systems, and targeted security holes in Microsoft Windows that have readily available patches.