The following notice has appeared on Wikipedia today when many UK users attempt to edit content:
"Wikipedia has been added to a Internet Watch Foundation UK website blacklist, and your Internet service provider has decided to block part of your access. Unfortunately, this also makes it impossible for us to differentiate between different users, and block those abusing the site without blocking other innocent people as well."
According to discussions on the Wikipedia administrators noticeboard, this is because a transparent proxy has been enabled for customers of Virgin Media, Be/O2/Telefonica, EasyNet/UK Online, PlusNet, Demon and Opal. This has two effects: users cannot see content filtered by the proxies, and all user traffic passing through the proxies is given a single IP address per proxy. As Wikipedia's anti-vandalism system blocks users by IP address, one single case of vandalism by a single UK user prevents all users on that user's ISP from editing. The effect is to block all editing from anonymous UK users on that list of ISPs. Registered users can continue to edit.
The content being filtered is apparently that deemed to meet the Internet Watch Foundation's critera for child pornography – in one case, this involves a 1970s LP cover art which, although controversial, is still widely available.
Reports on the admin noticeboard say that this filtering is easy to circumvent, either by using Wikipedia's secure server or by sending a request to find the page via parameters in the URL. However, no fix has been found – nor is one expected – for the proxy address problem.
"This is the first I've come across UK wide internet censorship, and I'm shocked. I had no idea until now that like China, we too have built a great firewall - only we keep quiet about ours.", user Hahnchen said, on the noticeboard.