The next type of firewall is Stateful inspection firewalls are often confused about packet- filtering firewall, but there is a huge difference between the two types of firewalls. The stateful inspection firewall is dynamic and monitors the state of active connections to determine which packets to go through the firewall (Dodis & Stephens-Davidowitz, 2016). Therefore, the stateful firewall is different from the packet-based firewall in that it provides a stable and reliable method of monitoring all active connections through a firewall, something that a packet-based firewall doesn’t do (Kenworthy, 2014). Having a stateful inspection firewall in an organization helps it to track all its active connections and to prevent any external attacks that may interfere with the origination’s operations.
This type of firewall stops each link at the firewall. If it is allowed, the connection to the destination is initiated on behalf of the creator of the initial connection. The connection type used in this firewall is known as a proxy, and if it is configured correctly, it can be transparent to the users (Pinter, 2015). This type of firewall works as a proxy server by providing proxies for specific applications. Every connection in this firewall is governed by specific rules and conditions like the one used by a packet-based firewall.
This firewall provides User Diagram Protocol (USD) and Transmission Control Protocol (TCP) security mechanism and works in an Open Systems Interconnection (OSI) model. Therefore, a circuit firewall provides a virtual circuit between a proxy server and the internal client in the organization by preventing direct connections between networks (Dodis & Stephens-Davidowitz, 2016). Consequently, an organization aiming at eliminating any internal data breaches can use circuit level firewalls. This firewall is developed to deal with the drawbacks of the application-gateway firewall by creating a seamless and transparent connection between the communicating parties as per the routines specified in a unique library (Cooper & Guzik, 2014). The connection is typically known as a virtual circuit, as it creates an end-to-end connection between the communicating parties. A tool known as SOCKS is used to implement this type of firewall (Pinter, 2015). Implementing this type of firewall is very tiresome, time-consuming, and costly as it involves changing all the clients to make them aware of the proxy mechanisms.