Stateful Firewall

A stateful firewall is any type of firewall that performs stateful inspection. It manages the state of connections such as TCP streams and other packets traveling across a network. A stateful firewall only allows packets that match to a known connection state to enter; all others will be blocked. Most stateful firewalls have the ability to track the state of data flows in protocols that don’t require a connection. UDP is such a protocol where sessions are typically labeled as an “established” state immediately after the first packet is detected by the firewall. Sessions in this type of protocol can only end as the result of a time-out. By keeping track of the network connection condition, stateful firewalls are able to provide an efficient means of packet inspection. This is made possible because the firewall only needs to check the state of existing connections instead of packets set by original configurations. Stateful firewall makes for a much quicker process and returns more reliable results.