Second Generation Firewall-Proxy Firewall

The proxy services act at the application layer. In essence, a proxy takes over the services between intranet users and Internet users. The working principle is that the proxy checks the request from a user. If the authentication is passed, the firewall sets up the connection to a actual server and forwards the request, and finally it returns the request response.

The proxy firewall has higher security. It can completely control network information exchanges and session processes.

However, it has obvious disadvantages:

• Low processing speed due to software restriction, and vulnerable to DoS attacks

• Difficult for upgrade as it requires developing the application proxy for each protocol