1. n. A dedicated gateway machine with special security precautions on it, used to service outside network connections and dial-in lines. The idea is to protect a cluster of more loosely administered machines hidden behind it from crackers. The typical firewall is an inexpensive micro-based Unix box kept clean of critical data, with a bunch of modems and public network ports on it but just one carefully watched connection back to the rest of the cluster. The special precautions may include threat monitoring, callback, and even a complete iron box keyable to particular incoming IDs or activity patterns. Syn. flytrap, Venus flytrap. [When first coined in the mid-1980s this term was pure jargon. Now (1999) it is techspeak, and has been retained only as an example of uptake --ESR] From Jargon Dictionary