The hackers pretended to be sending messages from the sites they intended to attack. When many computers simultaneously responded to sites like eBay, the overload of information shut down the real, unsuspecting sites.

This method also amplified the amount of information arriving at eBay, making the assault even more powerful.

In order to prevent such an attack from happening again, the Stanford system administrators have turned off the function that lists the broadcast, or return, address. On all other Stanford systems, this function is already off, but somehow Hopkins was overlooked, Brumley said.

The computers' response was not a malfunction, however, and there were no interruptions in service on the main Stanford network, though Hopkins slowed considerably, bringing the assault to administrators' attention.

While Brumley said that this function was overlooked on this particular system, he does not foresee any specific changes in security management in the future.

"We have a dedicated staff," he said, "and we continuously monitor the system."

Stanford's computers were only a few of "hundreds, if not thousands" used in the attack, Brumley said.

But Stanford administrators were among the few to admit that their computers were exploited.