The hole is a networking protocol called "NetBIOS," and if you don't know it's there -- or, say, if you've inadvertently instructed it to open your computer to the world (it happens) -- it's more like a gaping maw. NetBIOS allows any number of computer users to make all or part of their system visible to others by configuring the control panel's network settings for file sharing, which entails little more than checking a box that says, literally, "I want to be able to give others access to my files." Nefarious virus propagators have long used the ill-considered vulnerability of home networks to spread their handiwork. In March of last year, according to an incident note from the Computer Emergency Response Team (CERT), vandals used so-called open shares to spread a worm that instructed the modems of infected computers to dial 911.

Advocates of uncensored file sharing, however, are now looking at open shares as a possible alternative to Napster, an easy-to-implement system that will allow music trading without the middleman. The only impediment is finding out who's got files to share. So along comes Share Sniffer, a software program released on Feb. 23 and created by a 40-year-old named Kerry Rogers. Share Sniffer scans a list of Internet protocol addresses for open computers. (A "sniffer" in gearhead-speak susses out various activities on a network.) Install Share Sniffer, enter a block of IP addresses to scan and walk away for a few hours; the program will then find all the computers on that portion of the Net with files open to the public, and alert you with a little "ka-ching" sound with each one. The nuts-and-bolts version is free, with various upgrades available for a cost of anywhere from $10 to $100.

Michael Pommerer, president of Share Sniffer Inc., insists that the release of the software wasn't timed to capitalize on the injunction against Napster. "We're so much more than Napster," he argues, but agrees that the program can be used to swap music in much the same way, without any of Napster's legal hassles. "Napster was cataloging information on users and retaining it," he says. "All Share Sniffer does is execute a call to Windows and register the response.

"Kerry developed this product way back in '95, when that kid who came up with Napster [Shawn Fanning] was in grade school," says Pommerer. "Kerry's got a BBS background, and his original intent was to post shares across the Web for people who develop shareware. It was only with the introduction of broadband services [cable and DSL] that it was feasible. That was the big push. We just think it's very important for people to be able to exchange information without censorship using the Internet."

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