YouTube was back up two hours after Pakistan, in an act of information
provincialism, inadvertently made the videosharing site inaccessible to users
around the world Sunday afternoon.
The blackout left network administrators and Internet activists wondering on
Monday how Pakistan’s actions, meant to restrict only its own citizens from
accessing YouTube, could have such widespread reverberations — and whether such
a disruption could be reproduced by someone with more malicious intent.
The incident began Friday, according to reports, when the Pakistani government
of Pervez Musharraf became worried that a video clip attacking Islam might
generate widespread unrest among its Muslim population. The government asked the
Pakistan Telecommunication Authority, which oversees the country’s Internet
providers, to cut off access to YouTube for the country’s estimated 8.2 million
That action is not unusual. China, Morocco and Turkey have all reacted to
potentially risky material posted to YouTube by blocking access to the site
within their borders.
But two critical errors allowed Pakistan’s action to echo around the globe for
at least a brief period on Sunday afternoon, according to Martin A. Brown, a
data engineer at the Renesys Corporation, an Internet monitoring company, which
posted a timeline of the incident on its Web site.
As part of its effort to block YouTube within the country, Pakistan Telecom
created a dummy route that essentially discarded YouTube traffic, sending it
into what Internet experts call a black hole.
Pakistan Telecom then made an error by announcing that dummy route to its own
telecommunications partner, PCCW, based in Hong Kong, shortly before noon New
York time on Sunday, according to Renesys.
PCCW then made a second error, accepting that dummy route for YouTube and
relaying it to other Internet providers around the world.
Internet service providers now had two conflicting online “roads” leading to
YouTube. But because an important online protocol called Border Gateway Protocol
favors longer routing addresses — they are thought to be more specific — at
least 97 major Internet providers and thousands of smaller ones chose the dummy
route, Pakistan’s black hole.
About 1 p.m. Sunday, according to the Renesys timeline, YouTube began working to
correct the error, in part by telling Internet service providers that they
should direct traffic around Pakistan’s dummy route. YouTube has removed the
video clip that had concerned Pakistani officials.
In a statement Monday morning, YouTube addressed the situation. “For about two
hours, traffic to YouTube was routed according to erroneous Internet protocols,
and many users around the world could not access our site,” said a YouTube
spokesman, Ricardo Reyes. “We have determined that the source of these events
was a network in Pakistan. We are investigating and working with others in the
Internet community to prevent this from happening again.”
Steven M. Bellovin, a professor of computer science at Columbia, said the same
Internet routing flaw had been exploited in the past by spammers and other
ne’erdowells, but he worried it could be more widely used now.
“If it’s a big site that’s affected, it will be spotted and dealt with within an
hour or so, as happened this time,” he wrote in an email message. “If it’s a
small site, it might take a lot longer to find someone who would think to look
Professor Bellovin said that efforts to upgrade Border Gateway Protocol within
Internet standards organizations were moving slowly and that he was not
optimistic improvements could be made quickly unless such incidents became more
Craig Aaron, communications director at Free Press, an Internet rights
organization based in Washington, said the organization was worried that the
tactic could be used to stifle free speech online.
“Maybe this Pakistan instance was an anomaly,” he said, “but it certainly should
be raising alarms that we should be paying a lot more attention to our
international Internet security.”
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