Which layer do circuit level gateway firewalls operate on?

Which layer do circuit level gateway firewalls operate on?

• A. Application Layer
• B. Transport Layer
• C. Session Layer
• D. Network Layer

Answer: (C)

Circuit level gateway firewalls operate primarily on the session layer of the OSI model. This layer is responsible for establishing, managing, and terminating connections between devices. Circuit-level gateways monitor the TCP handshake and track the state of the connection to determine if a session is legitimate but do not inspect the actual content of the packets. They allow packets to flow freely once a connection is established, providing a level of security based on the legitimacy of the communication session rather than analyzing the content itself. This is distinct from other layers; for instance, application layer firewalls inspect the data included in the application payload, while network layer firewalls manage IP traffic and address-based rules without concerning themselves with the sessions. Transport layer firewalls would generally focus on TCP/UDP traffic without the session management aspects. Therefore, the correct answer emphasizes the role of the session layer in managing established connections for circuit-level gateway firewalls.

Circuit level gateway firewalls operate primarily on the session layer of the OSI model. This layer is responsible for establishing, managing, and terminating connections between devices. Circuit-level gateways monitor the TCP handshake and track the state of the connection to determine if a session is legitimate but do not inspect the actual content of the packets. They allow packets to flow freely once a connection is established, providing a level of security based on the legitimacy of the communication session rather than analyzing the content itself.

This is distinct from other layers; for instance, application layer firewalls inspect the data included in the application payload, while network layer firewalls manage IP traffic and address-based rules without concerning themselves with the sessions. Transport layer firewalls would generally focus on TCP/UDP traffic without the session management aspects. Therefore, the correct answer emphasizes the role of the session layer in managing established connections for circuit-level gateway firewalls.