What does stateful multilayer inspection in firewalls combine?

Stateful multilayer inspection in firewalls merges several critical components to enhance security. It integrates packet filtering with the capabilities of both circuit-level gateways and application-level firewalls.

Packet filtering is foundational and allows the firewall to check packets against predetermined rules. However, stateful inspection goes beyond mere packet filtering. It maintains the state of active connections and uses that information to determine which packets should be allowed through the firewall based on the context of traffic flow.

Circuit-level gateways come into play by monitoring TCP handshakes to allow sessions, ensuring that connections are legitimate before allowing data packets through. On the other hand, application-level firewalls inspect the data payload within packets to recognize applications and detect attacks that target specific software vulnerabilities.

This combination provides comprehensive coverage against various types of cyber threats, as it allows the firewall not only to filter data but also to maintain awareness of the state of connections and enforce security at a more granular level. Thus, creating a robust multilayer security model.

In contrast, the other options do not accurately reflect the components involved in stateful multilayer inspection. For instance, user authentication and encryption do not play a direct role in the packet filtering mechanism, while traffic analysis and system health checks are more related to network monitoring and performance rather