A proxy firewall is a network security system that protects network resources by filtering message at the application layer.
A firewall proxy server is an application that act as an intermediate between two end systems.
Firewall proxy servers operate at the application layer through the proxy.They do this bye creating and running a process on the firewall that mirrors a service as if it were running on the end host.
A firewall proxy server essentially turns a two party session into a four party session with the middle process emulating the two real hosts.
Because they operate at the application layer,proxy servers are also referred to as application layer firewalls.
A proxy service must be run for each type of internet application the firewall will support proxy servers are almost always one way arrangement running from the internal networks to the outside networks.
In the other words if an internal user wants to access a website on the internet, the packets making up the request are processed through the HTTP server before being forwarded to the website.
Firewall proxy servers centralize all activity for an application into a single server.