Cleanfeed (content blocking system)

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For other uses, see Cleanfeed.

Cleanfeed is a content blocking system implemented in the UK by BT, Britain's largest Internet provider, which targets only child sexual abuse content identified by the Internet Watch Foundation. All UK ISPs will be obliged to implement a version of it by the end of 2007^{[citation needed]}. Another system used by different ISPs is WebMinder. [1]

Cleanfeed was created in 2003 and went live in June 2004. [2]

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 [www.iwf.org.uk] 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.

1 Technical implementation
2 Filtering comparison
3 See also
4 External links

[edit] Technical implementation

There is a blacklist containing URLs to be blocked. Using Border Gateway Protocol (BGP), routers on the backbone redirects traffic to IP addresses that match domains that appear in URLs in the blacklist to special HTTP proxy servers (the technique is called BGP Shunt). These proxy servers then do the actual filtering by matching HTTP requests to URLs on the blacklist. Traffic which does not match the specific URL is forwarded through the proxy filter.

[edit] Filtering comparison

The other popular way of blocking content is DNS manipulation. Compared to this, Cleanfeed has the following properties:

Harder to circumvent. But still not that hard. Users can use proxy servers. Servers can use another port than 80.

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. E.g., it would be possible to block only one image in an article.