A firewall that filters traffic based on the state of the connection is known as?

A.  Packet filtering firewall

B.  Proxy firewall

C.  Stateful firewall

D.  Web application firewall

Answer:  C

Explanation:

A Stateful firewall keeps track of the state of active connections and makes decisions based on the context of the traffic, rather than just the source and destination. It examines not just the header information but also the contents of the packet up through the application layer, maintaining a state table that keeps track of all legitimate connections. This allows it to determine whether an incoming packet is part of an established connection, a new connection, or not part of any permitted connection.

Here's a breakdown of the other options:

Packet filtering firewall: This type of firewall filters packets primarily based on source and destination addresses, and sometimes port numbers. It doesn't keep track of the state of the connection.

Proxy firewall: A proxy firewall serves as an intermediary between internal and external network traffic. While it can offer a high level of security, it doesn't filter traffic based on the state of the connection.

Web application firewall (WAF): This type of firewall specifically focuses on protecting web applications by filtering and monitoring HTTP/HTTPS traffic between a web application and the Internet. It doesn't operate based on the state of connections but rather looks for known vulnerabilities at the application layer.

Therefore, a firewall that filters traffic based on the state of the connection is known as a Stateful firewall.