UNDERGROUND

One night, Electron and Phoenix decided to break into Spaf's machine at Purdue to steal a copy of Deszip. Phoenix would do the actual hacking, since he had the fast modem, but he would talk to Electron simultaneously on the other phone line. Electron would guide him at each step. That way, when Phoenix hit a snag, he wouldn't have to retreat to regroup and risk discovery.

Both hackers had managed to break into another computer at Purdue, called Medusa. But Spaf had a separate machine, Uther, which was connected to Medusa.

Phoenix poked and prodded at Uther, trying to open a hole wide enough for him to crawl through. At Electron's suggestion, he tried to use the CHFN bug. The CHFN command lets users change the information provided – such as their name, work address or office phone number – when someone 'fingers' their accounts. The bug had appeared in one of the Zardoz files and Phoenix and Electron had already used it to break into several other machines.

Electron wanted to use the CHFN bug because, if the attack was successful, Phoenix would be able to make a root account for himself on Spaf's machine. That would be the ultimate slap in the face to a high-profile computer security guru.

But things weren't going well for Phoenix. The frustrated Australian hacker kept telling Electron that the bug should work, but it wouldn't, and he couldn't figure out why. The problem, Electron finally concluded, was that Spaf's machine was a Sequent. The CHFN bug depended on a particular Unix password file structure, but Sequents used a different struc- ture. It didn't help that Phoenix didn't know that much about Sequents – they were one of Gandalf's specialties.

After a few exasperating hours struggling to make the CHFN bug work, Phoenix gave up and turned to another security flaw suggested by Electron: the FTP bug. Phoenix ran through the bug in his mind. Normally, someone used FTP, or file transfer protocol, to transfer files over a network, such as the Internet, from one computer to another. FTPing to another machine