FIREWALL

This term refers to security measures designed to protect a networked system from unauthorized or unwelcome access. The term is used in a more general sense than its original usage as a "firewall machine." Originally a firewall was a dedicated UNIX gateway machine with special security barriers. It protected other machines on web connections and dial-in lines. The idea is to protect a LAN of more loosely administered machines hidden the firewall from hackers, crackers, and phreakers . Incoming packets from the web are met with firewall barriers of various types that trash packets not allowed behind the firewall machine. Intranet firewalls are discussed at http://intrack.com/intranet/firewall.shtml . Terminology and firewall frequently asked questions (FAQs) are at http://www.seas.upenn.edu/~shinj/tcom500/glossary.html . Links to web safety can be found at http://www.pbs.org/internet/relatedsites/bs/index.html .