Which type of firewall tracks the state of network connections and makes decisions based on the context of the traffic?

A stateful firewall is designed to monitor the state of active connections and make decisions based on the context of the traffic, which includes information about the ongoing communication session. Unlike stateless firewalls, which treat each packet in isolation without keeping track of established connections, stateful firewalls maintain a table of active connections. This allows them to allow or block packets based on their state and context, providing a more nuanced level of security.

For instance, if a packet is part of an established connection that the firewall has validated, it can be permitted based on the state of that connection rather than just the rules regarding the specific port or protocol. This is particularly useful for dynamically handling protocols that require multiple packets to establish communication, such as TCP, where connections must be opened before any data can be exchanged.

Other types of firewalls, such as stateless firewalls, only evaluate packets against predefined rules without awareness of previous packets or sessions, and application firewalls work at the application level, filtering traffic for specific applications rather than tracking state at the network connection level.