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Intro to Content Filter
The Content Filter monitors the inbound Internet traffic and blocks inappropriate material from view by the browser. The Content Filter can be used not only to block inappropriate material, but also to enforce company policies. For instance, blocking personal webmail sites can increase productivity at the office. It is a way to block un-desirable and non work related browsing on the company's time and resources, an example of that being blocking "Facebook" and "Twitter" during company hours.
Benefits of Content Filter
Content Filter benefits the organization by improving productivity and reducing liability. Entertainment and news sites can be blocked so that users spend their time working instead of browsing. Content Filter can also be used to keep inappropriate material such as pornography, gambling, or violent content off the network. This not only improves productivity, but reduces potential liability an employer may have to control content and activity in the work place.
The Content Filter may also be configured with user specific or computer specific policies that apply permissions or restrictions based on content types or a time of day. These powerful controls (Access Control Lists) give you the ability to keep your network protected from inappropriate content based on the needs of the individuals.
How Content Filter Works
Content Filter has two capabilities - white/grey/black list and contextual word reference. White/grey/black list is an authorized list of web site URLs with approved (white), scrutinized based on individual pages within the site (grey), and unapproved (black) sites. This list needs to be maintained regularly because new sites appear, old sites disappear and current sites move around. By enabling the Content Filter service, you will receive regular updates to the filter lists. The contextual word reference process reviews the words contained on a specific page for inappropriate words and phrases. Approved sites that introduce inappropriate content can also be blocked. The updates are maintained by human editors and not by automated computer "spiders". This improves the accuracy of the blocking schemes.
We use an award winning Open Source web content filter which filters the actual content of pages based on many methods including phrase matching, PICS filtering and URL filtering. It does not purely filter based on a banned list of sites like certain other filters, but a content scanner which means that all websites are scanned for words/phrases/picture names etc and blocked if it has offensive content. You are able to block users from downloading specific types of files from websites.
It is completely flexible and allows you to tailor the filtering to your exact needs. It can be as draconian or as unobstructive as you want. The default settings are geared towards what a primary school might want but we put you in control of what you want to block. The main features are as follows:
- Can block adverts by the use of an advert URL block list.
- Can filter text and HTML pages for obscene (sexual, racial, violent, etc) content.
- Uses an advanced phrase weighting system to reduce over or under blocking.
- Can filter sites using the PICS labeling system.
- Can filter according to MIME type and file extension.
- Can filter according to URLs including Regular Expression URLs.
- URL filtering is compatible with squidGuard black lists.
- The URL filtering is able to filter https requests.
- Can work in a 'whitelist' mode where all sites except those listed are blocked.
- Can block all IP based URLs.
- Is able to block sites when users try using the IP address of the site instead.
- Produces a log in a very human readable format.
- Optionally produces a log in CSV format for easy import into databases etc.
- Is able to log the username using either Ident or basic proxy authentication.
- It has the ability to switch off filtering for specified sites, parts of sites, browser IPs and usernames.
- Can block specified source IPs and usernames.
- Can block or limit web uploading (e.g. attachments in Hotmail).
- Has the ability to work in a stealth mode where it logs sites that would have been blocked, but does not block them. This allows you to monitor your users without them knowing.
- Uses a very intelligent algorithm to match phrases in web pages mixed in with HTML code and white space.
- The configuration lists use the same incredibly fast code that allows them all to be hundreds of thousands of entries long.
- Supports (adds) the squid X-Forwarded-For header line.
- Supports compressed (Content-Encoding gzip and deflate) HTML.
- Can be made to only listen on 1 IP.
- Can stop downloading of Zip files etc
- With the use of blacklists, can block over 1.5 million sites which is reguraly updated
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