It was a peculiar situation. The automation system at a major manufacturing plant required constant communication with a server that controlled plant operations. Unfortunately, the server responsible for the heartbeat activity of the manufacturing system was ailing, throwing I/O errors willy-nilly, and showing all the signs of a rapid and violent death. Dozens of workers on the shop floor were left to the mercy of this server, trying to meet a critical deadline for product delivery, with no way to shut down the manufacturing process for even a moment, as it took hours to get everything back up to speed.
The server sent no instructions to the shop gear, but if the shop gear sent a heartbeat that wasn't acknowledged, the system would go into safety mode, shutting down all operations. The heartbeat process was still running in RAM on the server, but given that the rest of the server was well on its way toward leaving the building, it was only a matter of time before the entire shop would shut down. It was time to roll up the sleeves and get into the guts of the system.
Quickly, a monitoring port was configured on the switch connected to the server, and the heartbeat traffic was surveilled for content. It turned out that the heartbeat was a simple TCP connection with a static challenge and response that occurred every 60 seconds.
Within a matter of an hour, start to finish, a Perl script was written to answer TCP connections on that particular port and emulate the heartbeat activity of the server. Then, a second after a heartbeat transaction was seen, a laptop running the Perl script was set to the IP address of the server, and the dying server was pulled out of service.
For the next day and a half, production continued without slowing and the production server was rebuilt on new hardware. All the while, that Perl script dutifully sent the A-OK to the manufacturing system, which was none the wiser.
Jackass IT stunt No. 6: Set client time zones remotely with PerlA sizable medical records company, with offices dispersed across the United States, performed a data center upgrade that brought state-of-the-art Citrix servers to handle all remote-office desktop sessions. All was well until it came time to roll out new thin clients to every office in the company -- all 48 of them.
The new clients were built on embedded Windows NT, as was the style at the time, and weeks were spent perfecting a gold image to push out to all the clients when they were deployed. The first dozen offices went like clockwork, with the new clients performing exactly as advertised. There was much rejoicing.