Which firewall focuses on the application layer and uses proxies to filter traffic, restricting traffic to services supported by the proxy?

• A. Passive Application-Level Firewalls
• B. NAT
• C. Application-Based Proxy Firewalls
• D. Honeytrap

Answer: (C)

Application-layer proxy firewalls operate by acting as an intermediary at the application level. They terminate the client’s connection and open a separate connection to the destination service, which lets them inspect the actual application protocol, commands, and content. Because the proxy only allows traffic for services it supports, it can enforce precise policies and restrict access to those specific applications. This proxy-mediated, application-focused filtering is what sets this type of firewall apart.

NAT translates IP addresses and doesn’t enforce application-level rules, so it doesn’t provide the same level of control. A honeytrap is a decoy system, not a firewall. A passive approach would imply monitoring rather than actively mediating traffic through a proxy, which misses the core capability of filtering via application-layer proxies.