SSC IMD SA Mock 03 – Question 175

Which of the following firewalls examine traffic and filter on application-specific commands such as http:post or http:get?

• Application gateways
• Stateful multilayer inspection firewalls
• Circuit level gateways
• Packet filters

Firewall classifications:
– **Application Gateways (Proxy Firewalls)**: Operate at the Application Layer (Layer 7 of the OSI model). They understand specific application protocols (such as HTTP, FTP, Telnet) and can inspect, parse, and filter application-level commands like `http:get`, `http:post`, or FTP commands.
– **Packet Filters**: Operate at Layers 3 and 4, inspecting only IP addresses, port numbers, and protocol types without understanding application payloads.
– **Circuit-level Gateways**: Operate at the Session Layer (Layer 5), validating TCP handshakes without application-layer payload inspection.

Hence, **Application gateways** is the correct answer.