Which type of firewall is the most common in use today?

The most common type of firewall in use today is a stateful inspection firewall. This type of firewall operates by keeping track of the active connections and their states, allowing it to filter traffic based on established connections. It monitors both incoming and outgoing traffic and makes decisions based on the context of the traffic flow. This capability enables stateful firewalls to provide a more robust security posture, as they can differentiate between legitimate packets and potential threats by considering the entire context of the communication, rather than just examining individual packets.

Stateful inspection firewalls also maintain a state table that records the state of all connections passing through the firewall, significantly enhancing the ability to enforce security policies. Their flexibility and effectiveness in real-time traffic monitoring make them a preferred choice for both individuals and organizations looking to secure network environments.

While web application firewalls and deep inspection firewalls provide important security features for specific applications or data types, they are not as widely deployed for general network traffic management as stateful inspection firewalls. Proxy firewalls, while effective in certain scenarios, tend to be less common overall when compared to stateful firewalls, which strike a balance between ease of use and comprehensive protection for most network environments.