How Does a Firewall Protect

Firewalls work by controlling the information that comes in and out of the network. By using the Application Proxy service, the flow of information to the network can be controlled. A proxy is an application program that permits or forbids access by accepting or rejecting requests sent to it. Only valid users can log in and pass through a proxy service. It works on the Application level of the OSI model . Another technique that can be used is Encryption. A firewall may also combine encryption to provide confidentiality and authenticity. However this feature never works alone but is always combined with one of the above methods.