What Is a Stateful Firewall?

A stateful firewall is a type of firewall that provides stateful packet inspection or stateful inspection capabilities.

Stateful firewall (Stateful firewall), a stateful packet inspection (SPI) or stateful inspection (stateful inspection) function

Stateful firewalls track the state of network connections (such as TCP streams or UDP communications) and can save important attributes of each connection in memory. These attributes are collectively referred to as the connection state and may include detailed information such as the IP address and port involved in the connection, and the sequence number of the data packet that passed through the connection. Stateful inspection monitors the status of incoming and outgoing packets and connections over time and stores the data in a dynamic state table. This cumulative data is evaluated, so filtering decisions are based not only on administrator-defined rules, but also on the context in which the previous connection was built and previous groupings that belong to the same connection.

Do most of the while establishing a connection

Separate packet filtering is not considered to provide adequate protection. To prevent effectively

A vulnerability in a single protocol decoder could allow an attacker to gain control of the firewall. This concern highlights the need to update firewall software.

Some stateful firewalls also increase the possibility that a single host may be tricked into an external connection. This possibility can only be completely eliminated by reviewing the host software. Some firewalls can be defeated in this way by browsing the web (using JavaScript or after clicking a button). ^[2]