| 10.3 |  | Filtering |
| 10.3.2 |  | URL filtering |

| URL filtering Basically, a URL is an electronic address. Every valid URL leads somewhere on the Internet, and as with other types of addresses, some lead to appropriate sites and others to inappropriate sites. For a variety of legal, security, and work efficiency reasons, it is often desirable for a company to monitor and control which sites network users are allowed to access. This point is illustrated by studies that suggest between the hours of 9 a.m. and 5 p.m. the following Internet usage was recorded:

- 30 to 40 percent of Internet surfing is not business related.
- 70 percent of all Internet porn traffic occurs.
- More than 60 percent of online purchases are made.

It is apparent that filtering which Internet sites that can be accessed from a company network is important. However, filtering all traffic is often not a viable option, because employees need access to certain sites in order to do their jobs. It is often necessary to filter URLs on a case-by-case basis.

URL filtering and the PIX Security Appliance
The PIX Security Appliance does not support selective URL filtering on its own. Instead, it relies on specialized URL filtering applications that are configured on separate servers. These applications provide URL filtering for the PIX Security Appliance, which enables network administrators to effectively monitor and control network traffic. The PIX Security Appliance is capable of working with three different URL filtering applications. They are Websense, N2H2, and SmartFilter.

When the PIX Security Appliance receives a request to access a URL from users, it asks the URL-filtering server to determine whether or not to return the requested URL. The URL-filtering server checks its configurations to determine whether the URL should be blocked. If the URL should be blocked, URL-filtering applications can display blocking messages or direct the user requesting the URL to a specified Web site.

Two commands are required in order to configure the PIX Security Appliance to recognize and work with a designated URL filtering server. These commands are the url-server and filter url commands.

The Command Reference examines long URLs and how to configure the PIX Firewall to deal with them.

| Web Links www.Websense.com/ www.n2h2.com/ http://www.securecomputing.com

| Lab Activity e-Lab Activity: URL Filtering This activity will demonstrate how to configure URL Filtering on the PIX Security Appliance.