What is the difference between stateful and stateless firewalls?

Stateful firewalls are distinguished by their ability to track the state of active connections and make decisions based on the context of the traffic flow. This means that stateful firewalls maintain a state table, where they store information about ongoing connections, including the source and destination IP addresses, ports, and the protocol being used. This functionality allows them to determine whether a packet is part of an existing connection or a new one and to apply security policies accordingly.

In contrast, stateless firewalls treat each packet in isolation without regard to the overall connection status or context. They do not maintain any state information; instead, they rely on predefined rules to allow or block packets. This makes stateless firewalls simpler and faster but less sophisticated in terms of security.

Understanding this distinction highlights the importance of the context in connection management, which enhances security and allows stateful firewalls to provide better protection against various types of attacks that exploit connection states.