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Circuit Relay Firewall
Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.
A circuit relay firewall is a type of security firewall (proxy server) that provides a controlled network connection between internal and external systems (that is, there is no "air gap"). A virtual "circuit" exists between the internal client and the proxy server. Internet requests go through this circuit to the proxy server, and the proxy server delivers those requests to the Internet after changing the IP (Internet Protocol) address. External users only see the IP address of the proxy server. Responses are then received by the proxy server and sent back through the circuit to the client. While traffic is allowed through, external systems never see the internal systems. This type of connection is often used to connect "trusted" internal users to the Internet. See "Firewall" and "NAT (Network Address Translation)" for more information.
Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.