Which type of firewall acts as an intermediary between users and servers, filtering traffic at multiple OSI layers?

The correct answer is the Proxy Firewall, which serves as an intermediary between users and servers, effectively filtering traffic at multiple layers of the OSI model. This type of firewall operates by intercepting requests from clients, forwarding them to the destination servers, and then relaying the responses back to the clients.

By functioning at the application layer (Layer 7), a Proxy Firewall can analyze the content of the traffic to assess the legitimacy and security before communication proceeds. It can provide more granular control over data being transmitted and can also perform activities such as content caching, authentication, and protocol filtering.

Additionally, Proxy Firewalls enhance network security by hiding the true IP addresses of clients and servers, thereby making it more difficult for attackers to target them directly.

In contrast, other types of firewalls focus either on specific OSI layers or operate based on predefined rules without the deep packet inspection capabilities that Proxy Firewalls possess. Host-Based Firewalls are installed on individual devices and manage traffic only for that particular device, while Stateless Firewalls evaluate packets based solely on fixed rules without maintaining a record of ongoing connections. Next Generation Firewalls, while capable of advanced functions, may not necessarily act as a proxy for traffic between users and servers in the same way.