Introduction to Content Filtering Proxy Server

Content Filtering Proxy Server: Content Filtering Proxy Servers are generally used with the Web Proxy servers and give more control over the data which going out and coming in on a network.The main purpose of these servers is to setup a filter on the data. It is generally used in corporate world and universities to filter certain type of content flowing out of the network.
Content Filter Proxy servers also support User authentication to control web access. To filter the content, it uses URL or DNS blacklists, URL regex filtering, MIME filtering, or content keyword filtering. 


How it filters the content:When a user request for a URL to access, the request is first pass to proxy server filter. In the filter, the URL is matched with the database of URL patterns. If the URL is matched a banned URL, the request is rejected. If the URL is unmatched then the webpage is fetched by the proxy but each page of the webpage is checked and matched with the blocked pattern. For example: some images or language filer on the page. If the content is rejected then an HTTP fetch error is returned and nothing is cached.


This proxy also stores log files which stores the history of web access by every users. These are also used to monitor the internet usage.