What type of firewall tracks open connection-oriented protocol sessions?

A stateful firewall is designed to track open connections and manage the state of active sessions for connection-oriented protocols such as TCP. This type of firewall monitors the state of active connections and makes decisions based on the context of the traffic, not just individual packets. Because it maintains a state table that records the state of network connections, a stateful firewall can determine if a packet is part of an established connection or if it is an unsolicited request. This enables more sophisticated security measures, as it allows the firewall to enforce rules based on the entire context of a communication session, rather than analyzing packets in isolation.

In contrast, a stateless firewall makes decisions based solely on predefined rules, evaluating packet headers against these rules without considering the packet's connection state. An application firewall operates at the application layer and can filter traffic based on application-level protocols, but it does not necessarily track sessions in the same way as a stateful firewall. A packet filtering firewall focuses on examining packets against a set of predefined rules but lacks the capability to track session states, making it less effective in handling connection-oriented protocols.

Therefore, the correct choice reflects the sophisticated nature of a stateful firewall in managing and tracking connections, offering robust protection suited for connection-oriented sessions.