China's Great Firewall spreads overseas

In February 2008, BGP information from Pakistan -- which had just blocked YouTube -- was shared internationally, effectively knocking Google's video site offline for millions of users.

In an e-mail message, Netnod CEO Kurt Erik Lindqvist said his company is not hosting the bad routes on its server. They were most likely changed by machines somewhere on the Chinese network, McPherson said.

The incident shows that BGP remains a major weak link in the Internet, Joffe said. "It's really disconcerting form a security point of view and from a privacy point of view."

This is the first time that this type of behavior has been made public, but it has apparently been going on for some time. In a discussion group post on Wednesday, Nominet Researcher Roy Arends said that he has been studying this issue for a year.

Arends has compiled a list of 20 domain names that will trigger the kind of bad results, reported by Ereche. Arends is keeping the names of those domains secret, but he did publish some of his data in his discussion post.

"I wanted to keep this internal, however, the cat is out of the bag now," Arends wrote.