Proxy firewalls are the most secure types of firewalls, but this comes at the expense of speed and functionality, as they can limit which applications your network can support.
The enhanced security of a proxy firewall is because, unlike with other types of firewall, information packets don’t pass through a proxy. Instead the proxy acts as an intermediary - computers make a connection to the proxy which then initiates a new network connection based on the request; effectively a mirror of the information transfer. This prevents direct connections and packet transfer between either sides of the firewall, which makes it harder for intruders to discover where the location of the network is from packet information.
A firewall proxy provides internet access to computers on a network but is mostly deployed to provide safety or security by controlling the information going in and out of the network. Firewall proxy servers filter, cache, log, and control requests coming from a client to keep the network secure and free of intruders and viruses.
In essence, proxies are gateway applications used to route internet and web access from within a firewall. Proxy servers work by opening a socket on the server and allowing the connection to pass through. There is often only one computer in a proxy firewall network with a direct Internet connection – other computers have access to the Internet using that computer as gateway. A proxy gateway receives a request from a client inside the firewall, and then sends this request to the remote server outside of the firewall. The response from the server is then read and sent back to the client. Usually, the same proxy is used by all of the client computers within a network – this enables the proxy to efficiently cache documents that are requested by multiple clients.