Filtering by South Korean Government of Pro-North Korean Websites

The latest OpenNet Initiative bulletin is out! There has been a lot of criticism of the blocking and South Korea may lift the ban on some sites. It will be interesting to see what effect, if any, the realization that they are blocking many more sites than the 31 they intended will have.

Major internet service providers in South Korea were ordered by the Ministry of Information and Communication (MIC) to block domestic access to 31 websites considered to be carrying propaganda favoring the North Korean regime. Tests undertaken by the ONI in December 2004 and January 2005 reveal that South Korean blocking extends to far more than the 31 web sites targeted by the orders. An additional 3,167 unrelated domain names hosted on the same servers as the blocked sites are also blocked. South Korea’s blocking clearly demonstrates one of the important, unintended consequences of implementing Internet filtering: thousands of websites that were never intended to be blocked, and that are completely unrelated to North Korea, have been filtered.

Blocking by IP address generally leads to the blocking of content that was never intended to be blocked since many thousands of domains can be hosted on a single IP. A good explanation can be found in the Federal District Court’s ruling (pages 14 -19) in the Pennsylvania filtering case. A previous ONI bulletin discussed this when filtering was introduced in India. Also, the same problem (or is it a feature?) has been documented in commercial filtering software as well. In the case of national filtering (or filtering at the ISP level), blocking by IP is often the easiest and cheapest mechanism available (see pages 37- 38) in the Pennsylvania ruling). Countries just starting to implement a national filtering strategy will often start with IP-based blocking.


  1. Kritik an Websperren in Südkorea

  2. one official told me recently that authorities are looking at ways [?] to allow access, “if only for academic purposes” … most anon proxies will still get through to the IPs

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