<networking> A dedicated gateway machine with special security
precautions on it, used to service outside network, especially
Internet, 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 microprocessor-based Unix machine with no
critical data, with 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, call-back, and even a complete iron box
keyable to particular incoming IDs or activity patterns.
