Chapter 27 Content Filtering
USG20(W)-VPN Series User’s Guide
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• Restrict Web Features
The USG can disable web proxies and block web features such as ActiveX controls, Java applets
and cookies.
• Customize Web Site Access
You can specify URLs to which the USG blocks access. You can alternatively block access to all
URLs except ones that you specify. You can also have the USG block access to URLs that contain
particular keywords.
Content Filtering Configuration Guidelines
When the USG receives an HTTP request, the content filter searches for a policy that matches the
source address and time (schedule). The content filter checks the policies in order (based on the
policy numbers). When a matching policy is found, the content filter allows or blocks the request
depending on the settings of the filtering profile specified by the policy. Some requests may not
match any policy. The USG allows the request if the default policy is not set to block. The USG
blocks the request if the default policy is set to block.
External Web Filtering Service
When you register for and enable the external web filtering service, your USG accesses an external
database that has millions of web sites categorized based on content. You can have the USG block,
block and/or log access to web sites based on these categories.
Keyword Blocking URL Checking
The USG checks the URL’s domain name (or IP address) and file path separately when performing
keyword blocking.
The URL’s domain name or IP address is the characters that come before the first slash in the URL.
For example, with the URL
www.zyxel.com.tw/news/pressroom.php
, the domain name is
www.zyxel.com.tw
.
The file path is the characters that come after the first slash in the URL. For example, with the URL
www.zyxel.com.tw/news/pressroom.php
, the file path is
news/pressroom.php
.
Since the USG checks the URL’s domain name (or IP address) and file path separately, it will not
find items that go across the two. For example, with the URL
www.zyxel.com.tw/news/
pressroom.php
, the USG would find “tw” in the domain name (
www.zyxel.com.tw)
. It would also
find “news” in the file path (
news/pressroom.php
) but it would not find “tw/news”.
Finding Out More
for content filtering background/technical information.
27.1.3 Before You Begin
• You must configure an address object, a schedule object and a filtering profile before you can set
up a content security policy.
• You must have Content Filtering license in order to use the function.subscribe to use the external
database content filtering (see the
Licensing
>
Registration
screens).
Summary of Contents for ZyWall USG20-VPN
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