Dynamic Content Analysis is the key technology that makes Guardian so much more effective than other filtering products.
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The Dynamic Content Analysis filter scans every web page for words and phrases from numerous categories of objectionable content, including pornography, violence, drugs, racial hatred and gambling. Any page containing unsuitable content will be blocked, even if it comes from a reputable source such as a major news site or search engine.
Most web filters (note we do not call them content filters) are actually URL filters, relying upon a huge blocklist of pre-categorized web sites and pages. A blocklist of several million entries may sound impressive until one takes into account that the web consists of tens of billions of web pages and millions more are created every day. The growth of the web is seemingly exponential –thus maintaining an accurate categorized URL index is an almost impossible task. Neither is a URL list foolproof, for if a user accesses the web via an external anonymous proxy server all web pages will appear to come from an acceptable source. Likewise most search engines will display links and page snippets from offensive or pornographic web sites, sometimes even when the search terms are totally inoffensive.
The solution is to examine the actual page content, not where it appears to come from. Guardian will block objectionable content regardless of its source.
Guardian web content filtering products incorporate a proxy server that processes all user requests for web pages. As web pages are received, the Dynamic Content Analysis engine compares the text against categorized word and phrase lists, looking for objectionable, non work-related and positive work-related content. Every time a match is made, a weighting value for the word or phrase is added to a page score. Matching of positive work-related phrases will offset the presence of words from other categories, to avoid the false blocking of medical related pages for example. Once the page score reaches a threshold blocking value then the page will be blocked and a \"Blocked Page\" message sent to the user\'s computer instead of the requested web page. Where Guardian stands above other true content filters is the speed at which the Dynamic Content Analysis engine works, a typical novel could be analyzed in just a fraction of a second.
Working in conjunction with existing user authentication systems such as Microsoft Active Directory®, users are assigned to Guardian filter group policy whose web browsing is controlled by configurable rule-sets. The blocking threshold for a content filter rule-set would be set appropriate to members of the group, typically being set very low for young children, a moderate value for high school children and higher still for most adults. Different word and phrase categories can be enabled or disabled for each group. System administrators can even add their own words and phrases into custom category lists to override Guardian\'s standard filtering behaviour, such as to block specific content that most organizations would not wish to restrict.
It is the speed and sophistication of SmoothWall\'s Dynamic Content Analysis technology that makes it possible for Guardian to analyze the page content; whereas most web filters only perform the quick and simple action of checking the page URL against a blocklist. Guardian is the \"true\" web content filter.
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