Concept of Web Traffic Filtering

Although the firewall's main purpose is to protect inside users from outside threats, the PIX firewall can also help control which Web sites internal users can access. The PIX firewall can be linked to a URL filtering server such as WebSense or N2H2, which provide Internet monitoring and URL Web site blocking if necessary.

1.The client opens a connection to a Web server and sends an HTTP GET message to access a Web page.

2.The PIX intercepts the call and forwards the request to the URL filtering server and the Web site at the same time.

3.The filtering server searches its database of Web sites to see whether the user has permission to access the Web site. In the meantime, the Web site is attempting to respond to the user's request.

4.If the URL server's response is yes, the PIX allows the Web site response to be forwarded to the requesting client. Otherwise, the Web site's response is dropped.