ZDNet is reporting that six British ISPs are filtering access to Wikipedia as a result of the site being added to the Internet Watch Foundation after accusations that it is hosting what some consider child pornography.
The filtered content involves the controversial 1970s record album cover from the German band Scorpions that features a naked prepubescent girl. The album, Virgin Killer, was banned in many countries when it was released until a replacement cover was created.
In an attempt to block access to the Wikipedia article, Virgin Media, Be Unlimited/O2/Telefonica, EasyNet/UK Online, PlusNet, Demon, and Opal began routing traffic through transparent proxies, which seems to have caused yet more problems.
According to the report, when UK users attempt to edit content on Wikipedia, they receive this notice from the site:
"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."
Because the ISPs are routing Wikipedia traffic through proxies the majority of Wikipedia editors appear to be coming from the same IP range. The result is that if Wikipedia bans a single customer from one of the ISPs for vandalizing the site, it bans every customer from that ISP. British Telecom does not appear to be filtering.
There is an ongoing discussion over on Wikipedia's administrators' noticeboard with a list of affected IP addresses, workarounds and updates.