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Chapter 31 Content Filtering
ZyWALL USG 100/200 Series User’s Guide
548
31.8 Content Filter Technical Reference
This section provides content filtering background information.
External Content Filter Server Lookup Procedure
The content filter lookup process is described below.
Figure 411 Content Filter 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 blocks, blocks and logs or just logs the request based on your
configuration.
Category This field shows whether access to the web site’s URL was blocked or allowed.
Click the column heading to sort the entries. Point the triangle up to display the
blocked URLs before the URLs to which access was allowed. Point the triangle
down to display the URLs to which access was allowed before the blocked URLs.
URL This is a web site’s address that the ZyWALL previously checked with the external
content filtering database.
Remaining Time
(minutes)
This is the number of minutes left before the URL entry is discarded from the
cache.
Remove Click the Delete icon to remove the URL entry from the cache.
URL Cache Setup
Maximum TTL Type the maximum time to live (TTL) (1 to 720 hours). This sets how long the
ZyWALL is to keep an entry in the URL cache before discarding it.
The external content filtering database frequently adds previously uncategorized
web sites and sometimes changes a web site’s category. Setting this limit higher
will speed up the processing of web access requests but will also make it take
longer for the ZyWALL to reflect changes in the external content filtering database.
Apply Click Apply to save your changes back to the ZyWALL.
Reset Click Reset to begin configuring this screen afresh.
Table 176 Anti-X > Content Filter > Cache (continued)
LABEL DESCRIPTION