What is the function of a Stateful firewall?

A Stateful firewall is designed to track the state of active connections and make decisions based on the context of those connections. This means that it can inspect all characteristics of a packet, not just the header information. By being state-aware, the firewall can determine whether a packet is part of an established session or if it's a new, unsolicited request. This capability allows stateful firewalls to provide better security than stateless firewalls, which only inspect packet headers without considering the context of the traffic flow.

The ability to analyze the overall state and the flows of connections enables stateful firewalls to enforce security policies that are more dynamic and intelligent, adapting to changing network conditions and providing a more comprehensive means of controlling legitimate and malicious traffic. Ultimately, this context-aware approach is what differentiates stateful firewalls from simpler filtering mechanisms.