Which firewall operates at Layer 5 and Layer 7 of the OSI model?

The firewall that operates at Layer 5 (the session layer) and Layer 7 (the application layer) of the OSI model is the Next Generation Firewall (NGFW).

Next Generation Firewalls combine traditional firewall capabilities with advanced features such as deep packet inspection, application awareness, and intrusion prevention. By working at higher layers of the OSI model, these firewalls can analyze and filter data not just based on headers and routing information (as traditional firewalls do) but also based on the contents of the data being transmitted. This capability allows NGFWs to identify and govern application traffic more effectively, providing better security controls.

Circuit-level proxy firewalls primarily operate at Layer 5, but they lack the ability to interpret application data found at Layer 7. Packet-filtering firewalls function at Layer 3 (network layer) and Layer 4 (transport layer), focusing on the packet header information without understanding application-layer logic. Stateful firewalls track the state of active connections but typically do not provide the extensive application-layer inspection and control offered by NGFWs.

Thus, Next Generation Firewalls provide comprehensive security mechanisms that leverage data from both the session and application layers, making them highly effective in modern network security environments.