What is circuit level gateway?
A circuit-level gateway is a firewall that ensures connection security between UDP (UDP = User Datagram Protocol) and TCP (TCP = TCP = Transmission Control Protocol) and between the transport and application layers of an Open Systems Interconnection (OSI) network model how the session shift works. In contrast to application gateways, circuit-level gateways monitor the TCP data packet handshake and the compliance with firewall rules and guidelines.
A proxy server is a security barrier between internal and external computers, while a circuit-level gateway is a virtual connection between the proxy server and the internal client.
For example, when a user web page access request passes through the switching gateway, basic internal user information, such as: B. the IP address, exchanged in order to receive proper feedback. Then the proxy server forwards the request to the web server. After receiving the request, the external server sees the IP address of the proxy server, but does not receive any internal user information. The web or real server sends the proxy server a correct response, which is forwarded to the client or end user via the circuit-level gateway.