it is important to note that host names, and not ip addresses, are used for all internet filtering functions for several reasons. there are two reasons for this:
1 many blocked sites operate server pools, where many machines service a single host name, making it impractical and difficult to add and maintain the numerical addresses of every server in the pool.
2 many sites included in the web site filter regularly change the ip address of the server to try to bypass the web site filters. this makes maintaining a current list subscription critical for effective content filtering.
figure 29 filter update window
click filter, and then select the filter update tab at the top of the window. a window similar to that in figure 29 is displayed.
1 website filter status
shows the status of the web site filter and the date it was last downloaded.
2 download now
click this button to download and update the web site filter immediately. this process may take a couple of minutes, depending on internet traffic conditions and requires a valid subscription to the web site filter.
2 automatic download
click this box to enable automatic, weekly updates to the web site filter. also, select the day of the week and the time of the day to download the new list. a valid web site filter subscription is required.
3 if filter list not loaded
there are two radio buttons that determine what happens if the filter list expires or if a download of a filter list fails:
1 block traffic to all websites except for trusted domains
select this option if only access to trusted domains should be available in the event of the filter list expiring or a download failing. see “setting up trusted and forbidden domains” on page 77 for more information.
2 allow traffic to all websites
select this option to provide open access to the internet in the event of the filter list expiring or a download failing.
since it is necessary to restart the internet firewall once the download is complete, which causes a momentary interruption of internet access, it is a good idea to download new lists when lan access to the internet is at a minimum.
click update to send the configuration data to the internet firewall.
once loaded, the creation date of the current active list is displayed at the top of the window.
because of the rapid changes on the internet, the web site filter expires 30 days after it is downloaded. once expired, the internet firewall operates as determined by the radio buttons described above.