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.