Inside Network Perimeter Security, Second Edition

Chapter 4. Proxy Firewalls

In this chapter, we introduce you to proxy techniques and how they have been used to create proxy firewalls. Proxy firewalls serve a role similar to stateful firewalls. Both are designed to allow or deny access between networks based on a policy. The method they use to accomplish this is very different, though. As described in the last chapter, with a stateful firewall, network connections flow through the firewall if they are accepted by the policy. This type of firewall acts like a router, passing packets through that are deemed acceptable. In contrast, a proxy firewall acts as a go-between for every network conversation. Connections do not flow through a proxy. Instead, computers communicating through a proxy establish ...