UK ISPs implement mass content filtering and break Wikipedia 9. December 2008 – 11:01 by Bengt Feil (TuTech Innovation GmbH)

There is no doubt that the large majority of internet users would agree that there has to be some sort of action against the proliferation of illegal content on the internet. The question is how this could be achieved without harming innocent and productive use of the web. In 2004 British Telecom in the United Kingdom went live with Cleanfeed, a content filtering system which targets material related to child sexual abuse identified by the Internet Watch Foundation. All other UK Internet Service Providers agreed on implementing a version of this system till the end of 2007. BoingBoing has posted a flowchart describing how Cleanfeed works in detail. The widespread use of this system since 2008 recently has produced its first major controversy:

The Cleanfeed system identified a certain picture on Wikipedia.org (an album cover by the band Scorpions) as being content related to child sexual abuse. The system is set up to block such content by blocking the IP address of the server providing the content for all costumers who use an ISP who has Cleanfeed implemented (which should be all UK ISPs by now). Wikipedia on the other hand provides one IP address to all persons who want to edit any article on the site. The result is that all costumers of UK ISPs are now unable to edit Wikipedia which “breaks” the purpose and a major function of the site. No internet user in the UK could for example start writing an article about this controversy on the Wikipedia.

This example shows the problems of widespread and general purpose filtering of internet content at the ISP level:

• The catch-all method of filtering often kicks of whole sites or in this case IP addresses from the internet. The problem is that a URL or an IP address does not at all correlate to a person or a specific web page.
• Even so the blocked picture in this case is illegal in the UK such filters have to be very strict to catch all targeted content, which consequently leads to many false positives (content which appeared to be illegal but actually is not).
• The technical methods used to block content vary from system to system but almost always have negative side effects. The designers of Cleanfeed may not have had the Wikipedia way of assigning IP addresses in mind when building the filtering system it broke an important function of the Wikipedia site. Or in other words: Such a system is like shooting a bug with a shotgun.
• There is a major privacy concern related to a system at the ISP level checking all URL requests by all clients.

As already stated in the beginning there is no doubt that certain kinds of content on the internet is illegal and in some cases even repellent, but mass content filtering at the ISP level does not fit the propose of fighting this kind of content. It may be better to educate individual internet users about how they can individually decide which content may be viewed on their computers or at least let users decided whether they want to be subject to a centralized content filtering system.

Tags: Cleanfeed, content filtering, inenglish, United Kingdom, Wikipedia