Cleanfeed (content blocking system)
Cleanfeed is the name given to various privately administered ISP level content filtering systems operating in the United Kingdom and Canada, and as of May 2012[update] undergoing testing in Australia with a view to future mandatory implementation. These government-mandated programs originally attempted to block access to child pornography and abuse content located outside of the nation operating the filtering system. (Offending Web sites in the nation are breaking the law; the sites are shut down rather than being blocked.) The sites blocked are considered potentially illegal; actual legality can only be determined in a court of law. In the UK the use of Cleanfeed was later extended to block websites that link to (without necessarily themselves hosting) copyrighted material distributed without its owner's authorisation.
United Kingdom 
Cleanfeed is a content blocking system implemented in the UK by BT, Britain's largest Internet provider, which (as of 2008) targeted only alleged child sexual abuse content identified by the Internet Watch Foundation. UK Home Office Minister Vernon Coaker instructed all UK ISPs to implement a version of it by the end of 2007 on a voluntary basis, or face legal compulsion.
Cleanfeed was created in 2003 and went live in June 2004.
As well as child sexual abuse content hosted around the world, the Internet Watch Foundation also takes reports from the public and IT professionals via its internet Hotline regarding criminally obscene content and content that incites racial hatred, hosted in the UK. This content is not included in the IWF URL list supplied to the online industry for blocking purposes.
In June 2011 the Motion Picture Association began court proceedings in an attempt to force BT to use Cleanfeed to block access to NewzBin2, a site indexing downloads of copyrighted content. BT was ordered to block access to the site in late July and in a later clarification, BT was given two weeks to implement the block starting at the end of October.
Technical implementation 
There is a confidential blacklist containing URLs of pages (not whole sites) to be blocked. A less confidential list of sites potentially containing blocked pages is available to ISPs. Routers on the edge redirect traffic to these sites to special HTTP proxy servers which perform the actual filtering by matching HTTP requests to URLs on the blacklist. Traffic that does not match the specific URL is forwarded through the proxy filter.
Chapter 7 of a research paper by Richard Clayton provides an overview of the Cleanfeed technology.
The routers at an ISP that has implemented Cleanfeed technology check traffic destination against a list of IP addresses of sites that are suspected of hosting filtered traffic. If there is no match, the traffic is directed to the content host:
If the site IP address is found in the list of suspected sources of unwanted material, the traffic is routed to proxies (highlighted as IWF proxies) that check the specific page against a confidential blacklist of pages.
This two-pass implementation reduces the load on the proxy servers by not requiring that all traffic pass through them.
Filtering comparison 
The other popular way of blocking content is DNS manipulation. Compared to this, Cleanfeed has the following properties:
- Slightly harder to circumvent, although users can use open proxies, or the Tor network, and servers can use another port than 80, or HTTPS.
- Less collateral damage. DNS-based blocking is criticized for blocking all content on a site with the same domain name. Cleanfeed only blocks what is explicitly blacklisted. For example, it would be possible to block only one image in an article.
Related surveys of opinion 
The first UK survey of Internet regulation was carried out in 2007 and 2008. 90.21% of the participants in the limited scale survey were unaware of the existence of CleanFeed; of those who had heard about it, only 14.81% percent understood it completely. 11.1% learned about CleanFeed from UK government statements, and 22.2 percent from BT's statements. 60.87% did not trust BT, and 65.22% did not trust IWF to be responsible for a silent content blocking system in the UK.
A majority of the participants preferred an open content blocking system targeting child abuse content, rather than no Internet regulation. More specifically, 65.2% would prefer to see a message stating that a given site was blocked, 57.3% would like to have access to a form for unblocking a given site, and 68.5% would prefer more frequent briefing by BT, IWF and the UK.
Cleanfeed in Canada is a voluntary Internet URL filtering list maintained by Cybertip.ca for use by participating ISPs. Eight major providers, representing approximately 80% of Canada's Internet users, have been using the list since November 2006 to block foreign websites.
Accessing child pornography online is illegal in Canada. Cybertip.ca is recognized by the federal government, provincial governments and domestic law enforcement agencies as able to assess the potential illegality of alleged child pornography online. The Cleanfeed system is not a law enforcement tool and does not log access to URLs on the list.
Proposed implementations 
As of May 2012[update]:
Cleanfeed in Australia is a proposed mandatory ISP level content filtration system. It was proposed by the Beazley led Australian Labor Party opposition in a 2006 press release, with the intention of protecting children who were vulnerable due to claimed parental computer illiteracy. It was announced on 31 December 2007 as a policy to be implemented by the Rudd ALP government, and initial tests in Tasmania have produced a 2008 report. Cleanfeed is funded in the current budget, and is moving towards an Expression of Interest for live testing with ISPs in 2008. Public opposition and criticism have emerged, led by the EFA and gaining irregular mainstream media attention, with a majority of Australians reportedly "strongly against" its implementation. Criticisms include its expense, inaccuracy (it will be impossible to ensure only illegal sites are blocked) and the fact that it will be compulsory. Cleanfeed is a responsibility of Senator Stephen Conroy's portfolio.
One of the criticisms of the use of Cleanfeed is its potential for censorship of materials outside of its intended remit. The lack of transparency regarding the use of Cleanfeed have led some to question how much control ISPs and government bodies could have over internet content within the countries of its use. For instance, the Home Office in the UK has apparently already asked for sites that glorify terrorism to be blocked leading some to liken the powers of censorship, available through use of Cleanfeed, to those employed currently by China.
Another criticism is that Newzbin claims to have successfully circumvented Cleanfeed following a court order forcing BT to censor the website over copyright infringement claims. This poses the question as to whether websites hosting child pornography could adopt similar measures to allow their users access to blocked content .
Finally, information has surfaced that suggests that Cleanfeed could potentially be manipulated to provide a blacklist of blocked websites. This is problematic as it could allow the dissemination of child pornography, rather than the prevention of access to it. Again this has led some to question Cleanfeed as a successful system for blocking illegal internet content.
See also 
- "BT ordered to block links to Newzbin 2 website". BBC News. 28 July 2011.
- Bright, Martin (6 June 2004). "BT puts block on child porn sites". The Guardian (London). Retrieved 30 April 2010.
- "Film-makers seek injunction to block pirate site". BBC News. 28 June 2011. Retrieved 28 June 2011.
- "UK ISP BT Given 14 Days To Block Newzbin2". TorrentFreak. 26 October 2011. Retrieved 31 October 2011.
- Clayton, Richard (November 2005). "Anonymity and traceability in cyberspace". Richard Clayton. Richard Clayton. Retrieved 10 December 2008.
- Hogge, Becky. "IWF censors Wikipedia, chaos ensues". Open Rights Group. Retrieved 2008-12-10.
- FirstMonday: Internet regulation: The need for more transparent Internet filtering systems and improved measurement of public opinion on Internet filtering, N Kopumartiz and A Veglis
- Book: BT's Cleanfeed and Online Censorship in UK, N Koumartzis, London College of Communication (University of the Arts London)
- Cleanfeed Canada
- ISPs and Tipline Step Up Battle Against Internet Child Exploitation
- Mountie hopes web initiative could cut child abuse
- ISPs to monitor child porn under proposed bill
- Liebhardt, John (2008-12-11). "Australia rallies to "Stop the Clean Feed"". Global Voices Online. Retrieved 2008-12-11.
- From child porn to China , in one Cleanfeed
- Newzbin claims BT block 'not working'
- Banned Piracy Website Expands BT Circumvention Tool to Include The Pirate Bay
- Failures in a Hybrid Content Blocking System
- Back door to the black list
- Internet Watch Foundation
- Richard Clayton: Anonymity and traceability in cyberspace" Cambridge Tech Report. Ch 7 deals extensively with Cleanfeed.
- Nikolaos Koumartzis: BT's CleanFeed and Online Censorship in UK: Improvements for a more secure and ethically correct system" MA thesis, London College of Communication, University of the Arts London.
- BBC News: Doubts over web filtering plans