What is the difference between a proxy firewall and a stateful inspection firewall?

A proxy firewall and a stateful inspection firewall are two different types of firewalls that provide different levels of security and functionality.

A proxy firewall acts as an intermediary between the internal network and the external network. It receives requests from internal users and forwards them to the external network on their behalf. When the response is received, the proxy firewall verifies its integrity and then forwards it back to the internal user. The key difference with a proxy firewall is that it establishes a separate connection with the external network on behalf of the internal user, effectively hiding the internal network's IP addresses and providing an additional layer of security. It can also inspect the content of the traffic passing through it, allowing for more granular control and filtering of network traffic.

On the other hand, a stateful inspection firewall operates at the network layer and keeps track of the state of network connections. It examines the headers and the context of network packets to determine whether they are part of an established connection or a new connection attempt. By maintaining a state table, it can make informed decisions about allowing or blocking traffic based on the connection's state. Stateful inspection firewalls are generally faster and less resource-intensive compared to proxy firewalls, as they do not need to inspect the content of each packet. However, they provide less granular control over network traffic compared to proxy firewalls.

In summary, the main difference between a proxy firewall and a stateful inspection firewall lies in their approach to handling network traffic. A proxy firewall acts as an intermediary, establishing separate connections on behalf of internal users and providing more granular control and filtering. On the other hand, a stateful inspection firewall focuses on examining the state of network connections and making decisions based on that information, offering faster performance but less granular control.