Inside Internet Filtering

The UK has a voluntary Internet filtering system that has been deployed by ISP’s.  The core of the system is blacklist powered by data from the Internet Watch Foundation.

In the last month or two the ISP filtering system in the UK has been scrutinized over two different filtering mistakes.

The first came when they effective blocked Wikipedia because of an image of on the cover of the Albulm Virgin Killer by the german heavy metal band The Scorpions.  Since the UK system works by filtering all suspect traffic through proxy servers, in this case all traffic to Wikipedia, editing of Wikipedia articles was not available to users in the UK because Wikipedia doesn’t allow proxy connections to edit Wikipedia for security reasons.

Most recently the Wayback Machine was blocked, but it appears to be only limited to one ISP this time.  The Wayback Machine is an archive of Internet sites that allows you to view old versions of websites.  There was a small amount of content in this archive that the Internet Watch Foundation felt should be blocked, but it led to the entire site being blocked by the British ISP Demon Internet.  It appears that the root cause of this block was an incorrectly configured proxy server and the problem was corrected within a few days.

I think these two incidents reflect some of the challenges ahead for Senator Conroy’s plan for country-wide ISP level filtering in Australia.  The Wikipedia incident shows how easy it can be for overblocking to occur. But in the case of the Wayback Machine, the list data from the Internet Watch Foundation seems to have contained only a small subset of the archive.  However a technical error on the part of hte ISP caused a larger issue.  I think we will see similar issues out of Australia if Senator Conroy’s plan becomes a reality.

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