What is the primary function of stateful packet filtering in network security?

The primary function of stateful packet filtering in network security is to monitor active connections. This type of filtering keeps track of the state of network connections, such as TCP streams and UDP communication, allowing it to make more informed decisions about which packets to allow or deny based on the context of the connection.

Stateful firewalls maintain a table of active connections and their states, checking incoming packets against this table. If a packet is part of an established connection, it will typically be allowed through, while packets that do not correspond to existing connections may be scrutinized or blocked based on established rules. This tracking capability enhances security by ensuring that only legitimate traffic that is part of a recognized session is permitted, helping to prevent unauthorized access and attacks.

Other options are not accurate in describing the primary function of stateful packet filtering. Blocking all inbound traffic would restrict legitimate communications, and allowing all traffic by default would pose significant security risks. Limiting traffic to specific protocols focuses on the type of traffic rather than maintaining the context of established sessions, which is not the primary role of stateful filtering.