For the first time, U.K. Internet service providers have censored a Wikipedia article, one that includes an album cover image of a naked and possibly underage girl.
An unintended side effect of the block left U.K. users of the online encyclopedia unable to edit other articles, Wikimedia said.
The article concerns the album "Virgin Killer" by German band The Scorpions. The record has generated controversy due to its cover photo ever since it was released in 1976.
The URL (uniform resource locator) of the article was added to a blacklist published by the Internet Watch Foundation (IWF), a nonprofit group that works with law enforcement to block and remove child pornography from Web sites.
Some 95 percent of U.K. ISPs use IWF's blacklist, although nonresidential Internet connections are not affected, according to the Wikimedia Foundation.
Adding the article to the blacklist caused the ISPs to route Wikipedia traffic through a proxy server, resulting in Wikipedia being unable to distinguish U.K. users from one another by their IP address. That triggered Wikipedia's anti-abuse mechanism, blocking all nonregistered U.K. users from editing articles, according to the foundation.
Two major ISPs, BT and Virgin Media, maintain the image should be removed as it has been classified as illegal by U.K. law enforcement.
Virgin Media funnels traffic from domains with pages listed on IWF's blacklist through a transparent proxy server, which blocks the offending page, according to a spokesman. Wikipedia appears to be blocking edits from people accessing its domain through a transparent proxy server, he said.
Although a user's real IP address is transmitted through the proxy, Wikipedia appears to only look at the proxy IP address and deny editing access based on that, the spokesman said. That access could possibly be enabled if Wikipedia's system configuration was changed, he said.
Wikipedia does use software called MediaWiki, which can interpret X-Forwarded-For (XFF) headers, which can pick out the real IP address rather than a proxy IP, said Mathias Schindler, a founding member of Wikipedia Germany and a volunteer with the Wikimedia Foundation communications committee.
According to Wikimedia's XFF information page, if a proxy server is on the organization's "trusted" list, users will appear to be editing from their client IP and not the proxy IP.
"Wikipedia administrators will be able to block clients individually; the whole proxy will never be blocked due to the actions of a single vandal," the page reads.
BT, which also uses the IWF blacklist, said if Wikipedia removes the image from the entry, "we can go back to the way things were," according to a spokesman. BT did not have a comment on the technical issue of why anonymous users can't seem to edit stories since the block was imposed.
A statement issued by IWF on Sunday said the album cover was flagged earlier this month and judged to be a "potentially illegal indecent image of a child under 18."
The Wikipedia image is hosted outside the U.K. The Wikimedia Foundation said online retailer Amazon.com also hosts an image of the original album cover, which is on many other Web sites accessed by U.K. citizens.
"We have no reason to believe the image has been held to be illegal in any jurisdiction anywhere in the world," a Wikimedia Foundation statement said.
A look at the history of edits to the Wikipedia story indicates a robust debate about the album cover has been going on since earlier this year.
A notice on the "discussion" section for the article read that the album cover will not be removed and advised that users who are offended should configure their browser to block it.