“The file-trading network’s developers are discovering that even their wide-open, free-for-all technology might need a little policing“:

Last September, the loose affiliation of programmers who monitor the Gnutella file-trading network noticed something strange. The network, a popular hub for MP3 traders, seemed to be suffering a kind of denial-of-service attack, with some people reporting that their machines were inundated with requests for content. Though the attack seemed small, the particular design of Gnutella — a “decentralized peer-to-peer network,” in which each computer routes network traffic — amplified its effects, causing the whole network to clog.

But when the developers got to the bottom of the problem, it turned out that there was no malicious attack — it was just selfish code. A new Gnutella client called Xolox

had recently come onto the network, and in an effort to give Xolox users faster downloads, its programmers had configured the program to frequently “re-query” the network to check for desired files. Such automated requests aren’t unusual — many programmers use the technique to improve their software’s performance on Gnutella; but Xolox re-queried at dizzying speeds, causing headaches for everyone else, while possibly improving downloads for its own users. Salon