What kind of inspection does a stateful firewall perform?

Stateful firewalls perform Deep Packet Inspection as they are designed to examine the state and context of network traffic. This means that they do not just look at the individual packets of data but also keep track of the state of active connections. By analyzing the headers and the data within packets, a stateful firewall can determine whether a packet is part of an established connection or if it is unsolicited traffic. It can inspect all layers of the OSI model, typically from layer 3 (Network) through layer 7 (Application), which allows it to enforce rules based on the entire context of network traffic.

Deep Packet Inspection enhances security by enabling detection of attacks and malicious content that may be hidden within the payload of packets. This level of analysis goes beyond basic filtering and is essential for protecting against more sophisticated threats that can bypass simpler firewalls that only perform packet filtering.

In contrast, the other types of inspection mentioned do not capture the full capabilities of a stateful firewall. Packet filtering typically refers to simple rule-based checks on packet headers without maintaining any state information. Application Protocol Inspection is more specialized in analyzing specific application protocols and may not encompass the full context of active connections like stateful inspection. Layer 4 Inspection generally focuses on transport layer information which is less