Circuit-Level Gateway is a type of firewall that provides session-level control over network traffic.
What is Circuit-Level Gateway?
Circuit-Level Gateway is a type of firewall that provides session-level control over network traffic. Similar in operation to packet filtering routers, circuit-level gateways operate at a higher layer of the Open Systems Interconnection (OSI) reference model protocol stack.
How does Circuit-Level Gateway work?
Circuit-level gateways are host-based and reside on individual clients and servers inside the network, rather than on a dedicated machine as they do with other types of firewalls. Circuit-level gateways examine incoming Internet Protocol (IP) packets at the session level – transmission Control Protocol (TCP) or User Datagram Protocol (UDP) – and act as relays by handing off incoming packets to other hosts.
Circuit-level gateways are rarely used as a stand-alone firewall solution; instead, they are typically used in combination with application layer proxy services and packet filtering features in dedicated firewall applications.
Microsoft Proxy Server combines the features of packet filtering, circuit-level gateways, and application layer proxy to provide a full firewall solution for protecting your corporate network. Proxy Server supports both the SOCKS protocol, which provides nontransparent circuit-level gateway security and the Winsock Proxy, which provides transparent circuit-level gateway security.