Circuit-level gateway

<p>A circuit-level gateway is a type of <a href="/facts/Firewall_(networking)/Et2RkJaU">firewall</a>.
</p><p>Circuit-level gateways work at the <a href="/facts/Session_layer/Yxo8uqLr">session layer</a> of the <a href="/facts/OSI_model/oxN9Xhjz">OSI model</a>, or as a "shim-layer" between the <a href="/facts/Application_layer/FAFhLruA">application layer</a> and the <a href="/facts/Transport_layer/UmIGUCeK">transport layer</a> of the <a href="/facts/TCP%2fIP/KNkxtSpw">TCP/IP</a> stack. They monitor TCP handshaking between packets to determine whether a requested session is legitimate. Information passed to a remote computer through a circuit-level gateway appears to have originated from the gateway. Firewall traffic is cleaned based on particular session rules and may be controlled to acknowledged computers only. Circuit-level firewalls conceal the details of the protected network from the external traffic, which is helpful for interdicting access to impostors. Circuit-level gateways are relatively inexpensive and have the advantage of hiding information about the private network they protect. However, they do not filter individual packets.
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Circuit-level gateway open-in-new

Circuit-level gateway