ZyXEL Communications Parental Control Gateway HS100/HS100W - Manual (Page 160)

HomeSafe User’s Guide
12-6 Parental Control
Table 12-1 Parental Control
LABEL DESCRIPTION
Reset Click Reset to start configuring this screen again.
12.5 Parental Control Group Edit Filter
The HomeSafe content filtering allows you to block services and block web sites by URL
keywords that you specify, for example, you can block access to all web sites with the word
“bad” in the URL by specifying “bad’ as a keyword.
12.5.1 Content Filtering with an External Server
Your HomeSafe uses an application services company that provides outsourced content filtering.
If you enable the content filter, your HomeSafe will have access to an external database, which
contains dynamically updated ratings of millions of web sites.
The content filtering lookup process is described below.
Figure 12-5 Content Filtering Lookup Procedure
1. A computer sends an HTTP request to a web server.
2. The HomeSafe 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 HomeSafe’s cache.
The HomeSafe either blocks or forwards the request based on how you configure the
category based content filtering.
The HomeSafe drops a URL record from the content filter cache after the content filter
cache timeout period (default 72 hours). All of the URL records are also cleared from the
local cache when the HomeSafe reboots. You can use ip urlfilter webControl cache
timeout on the command line to change the timeout period.
If the HomeSafe doesn’t have a record of the web site, it will query the external content
filtering server and simultaneously send the request to the web server.
The external content filtering database may change a web site’s category or rate a
previously uncategorized web site.
3. The external content filtering server sends the category information back to the
HomeSafe, which then either forwards or blocks the web content. The web site address is
then also stored in the HomeSafe’s content filtering cache.
Pre-defined categories have a filtering process based on ports and services.
1. A computer sends service-based request.
2. The HomeSafe looks up the port that this service uses.