Content Filtering With An External Database; Categories And Registering; Figure 89 Content Filtering Lookup Procedure - ZyXEL Communications ZyWall 35 User Manual

ZyWALL 35 User's Guide

11.3 Content Filtering with an External Database

When you register for and enable external database content filtering, your ZyWALL accesses
an external database that has millions of web sites categorized based on content. You can have
the ZyWALL block, block and/or log access to web sites based on these categories. The
content filtering lookup process is described below.

Figure 89 Content Filtering Lookup Procedure

1 A computer behind the ZyWALL tries to access a web site.
2 The ZyWALL looks up the web site in its cache. If an attempt to access the web site was
made in the past, a record of that web site's category will be in the ZyWALL's cache. The
ZyWALL block, block and log or just log the request based on your configuration.
The ZyWALL drops a web site address record from the content filter cache after the
content filter cache timeout period (default 72 hours) expires. All of the web site address
records are also cleared from the local cache when the ZyWALL restarts. You can use ip
urlfilter webControl cache timeout on the command line to configure
how long a web site address remains in the cache.
3 If the ZyWALL has no record of the web site, it will query the external content filtering
database and simultaneously send the request to the web server.
The external content filtering database may change a web site's category or categorize a
previously uncategorized web site.
4 The external content filtering server sends the category information back to the
ZyWALL, which then blocks and/or logs access to the web site. The web site's address
and category are then stored in the ZyWALL's content filtering cache.

11.4 Categories and Registering

To register for and configure category-based content filtering, click CONTENT FILTER,
and then the Categories tab to display the screen shown next. Use this screen to enable
external database content filtering and select which web site categories to block and/or log.
You must register for external content filtering before you can use it
Filtering Registration and Reports
210
for detailed information).
Chapter 11 Content Filtering Screens
(see Chapter 12 Content