In the late 1980s, Andrew Harkavy was working as a lead developer for a large hotel chain. He was responsible for 240 hotels that ran off 4 regional minicomputers. Each minicomputer served around 60 hotels, with six ports designated for each one for its terminals, printers, IT dial-in support, etc. Most of the time things worked pretty well, though the hardware was being pushed to the limit.

One day, Andrew got a call from a hotel employee with a strange issue — the screen's output kept coming out of the printer. Some time later, Andrew got another call from the same hotel employee, this time it was print jobs being output to the screen.

Calls trickled in from hotel staff from other hotels that were connected to the regional computer. Andrew dialed in to the system using its port that was dedicated to IT dial-in support. Their passwords changed daily, so he looked up the day's password and typed it in.


After some debugging, Andrew discovered the issue — some of the port numbers had shifted, causing what should be screen output to be sent to the printer. Andrew found a way to reset the port numbers, which made the problem disappear. For a few months.

The problem appeared again on a busy summer day. The hotels were getting a lot of traffic from families on summer vacations, and the servers were getting hammered. Andrew answered a frenzied call from one of the hotels and immediately dialed in to the server to reset the port numbers. He checked the day's password and logged in.


After hitting enter, he noticed his typo and waited for another login prompt. Instead, he was automatically disconnected with the following warning:

|                                                                |
| WARNING !!         HACK ATTEMPT DETECTED !!         WARNING !! |
|                                                                |

Andrew's heart skipped a beat, and then he started laughing to himself. His team had written the warning to scare wardialers off, and despite their initial concerns that no one would believe it, Andrew had fallen for it for a second. Andrew reconnected, reset the port numbers, and disconnected.

A few weeks later, the problem appeared again. The port numbers switched, and mass confusion spread among the hotel staff. In an even more frenzied panic than usual, someone from the front desk phoned Andrew.

"Help! The front desk computer is calling the police!"