Filtering Content from HTML Pages

The HTML Content Filtering Setup Screen (Figure 4.38) allows you to specify what types of HTML content you would like to have filtered out of web pages. Content filtering only works with proxy HTTP access, not transparent access; however, the firewall will use a special kernel modification to make access appear transparent if an HTTP gateway is configured rather than a proxy. In this case, content filtering will only be done for accesses to web servers on port 80, so it is recommended that you rather explicitly configure web access to be via a proxy if you want to use content filtering.

The types of content that can be filtered are Java and JavaScript, VBScript (Microsoft Visual Basic), and Active/X. If you are concerned about active content, it is a good idea to filter out all of these, with the possible exception of JavaScript. Enabling banner ad filtering will filter out links to sites listed in the Blocked Banner Ad Sites Screen.

  

Figure 4.38: The HTML Content Filtering Setup Screen

The available functions are:

F1

Cancel and return to the Access Setup Screen

F2

Edit the list of banner ad sites to filter

F7

View help

F8

Save changes and return to the Access Setup Screen