Pakistan’s Internet has a bad weekend

This was a dark weekend for the Internet community in Pakistan. A series of unfortunate events started with an order for ISPs to block YouTube in Pakistan, which naturally riled citizens and advocates of free speech. Making things worse, the implementation of the block by one of the ISPs made YouTube inaccessible to most of the Internet around the world for two hours. Inadvertently, much of the global Internet audience has now experienced filtering.

On February 22, a ministry-level order was sent to Pakistani ISPs to block YouTube, ostensibly in reaction to a video making fun of the Prophet Muhammad. Without investing in expensive filtering technology, there are two ways to block access to a web site, IP blocking and DNS tampering (more explanation here). Neither of these techniques permits the selective blocking of individual video clips.

Pakistan Telecom, a major ISP, chose to block YouTube by advertising part of YouTube’s assigned network as its own. This means that the request for YouTube.com could resolve to one of its servers instead of the YouTube servers. In order for this real estate masquerade to work, this new routing information has to be disseminated around Pakistan. Unfortunately, they advertised this switch to the Internet at large. ISPs around the world began routing to Pakistan Telecom’s servers instead of YouTube’s.

This mistake rendered YouTube inaccessible to users around the world for anywhere from half an hour to 2 hours last night. YouTube responded by announcing the problem and international ISPs began to correct the problem, reverting to the proper routing of YouTube traffic. Renesys blog has a timeline of the outage and an explanation of some of the technical details.

Adding to the ISPs embarrassment, PCCW Global, Pakistan Telecom’s upstream provider, took Pakistan Telecom offline completely.

As Steve Bellovin points out, this sort of “hijacking” is not new. Spammers do this intentionally and maliciously to gain access to new IP ranges. There are also several notable events such as this one where it was done by mistake. As Jonathan Zittrain points out to us, trust – that a URL or domain name is what it says it is – is an essential part of the health of the Internet. This event also shows how vulnerable a system that relies on trust can be.

The ramifications of this are partly temporary—the outage was based upon human error, and we don’t expect to see this repeated often (especially now). However, there may be more lasting outcomes, which are worth mention. It is possible we could see Pakistan join the growing list of countries that ask YouTube to filter the site selectively in that country. Thailand and Turkey have already asked for this, to restrict access to videos that that offend the Thai king and Ataturk, respectively. Filtering for videos that disparage the Prophet Muhammad are analogous. However, the motivation for the original blocking in Pakistan is not clear, and there have been allegations that this block is not totally motivated by videos of the Prophet Muhammad; there are new videos of vote rigging and those that contain other political opposition content. The timing of the YouTube block order is somewhat suspect given that blasphemous content has been available for some time and is still available on other sites in Pakistan, including Wikipedia.

Filtering in Pakistan has also been problematic within the country, with ISPs using IP blocking to restrict access to several blasphemous sites in the past year bringing down access to millions of sites, in a large case of collateral filtering. Look for the forthcoming ONI bulletin on this issue.

In this instance, the collateral damage of Internet filtering affected users of one the Internet’s most popular sites around the globe. Many who may have regarded overseas filtering with complacency thus far now have had first-hand experience with filtering and the damage it can have to the overall health of the network. For Internet users at large, this event lays open the fragility of the Internet. For Pakistan, the story of YouTube blocking is far from resolved.