C GATE Collaborative Virtual Workspace Comprizon. A Primer A firewall is a process that filters all traffic between a protected or inside network and a less trustworthy or outside network.
Firewalls implement a security policy.
A firewall is a gateway which all traffic passes through to and from a protected network. Proxy gateways have a richer set of choices for security policy. A guard is a sophisticated proxy firewall. Guards decide what services to perform on a users behalf. Firewall architectures can operate at the application layer, transport layer or network layer of the OSI model.