How Pakistan Hijacked YouTube

Posted on February 26, 2008
Filed Under Internet, Networking |

On February 24, 2008 in response to a government order, a Pakistani ISP (Internet Service Provider, a business that provides access to the Internet such as Bell, Cogeco, and IAW) PieNet, began blocking access to a YouTube video that apparently contained blasphemous content. Unfortunately the block affected more than just Pakistan and some estimates are that that it affected a third of the planet from reaching YouTube for almost two hours in some cases

From a technical standpoint it is fascinating — and a bit scary — that a single ISP in some far off place can arbitrarily deny access to an Internet site for users even beyond their borders. The question of censorship, religion, and politics all have a place in this story but for me the interesting thing is how that single ISP was able to effect such damage and the fragility of the Internet it suggests.

The Internet is a very large – it is in fact the largest – computer network and in many ways it is very similar to the telephone network we all take for granted. In the old days an operator would take calls (I can’t get that picture of Lily Tomlin as Ernestine out of my mind) and would plug the right wire into a switchboard to connect a call. It’s not a great deal different today except that the process is automated and electronic “switches” replace human operators in routing phone calls. The switch knows how to connect a call based on the country code, area code, and the phone number that was dialled.

Computers on computer networks are able to communicate similarly to telephones by using “IP addresses” rather than telephone numbers. If I want to bring up www.youtube.com on my computer, I type www.youtube.com into my web browser and my computer looks up the IP address for www.youtube.com just like I would look up a phone number in the phone book. Fortunately the mechanics of looking up the IP address is done entirely in the background by the computer or in other words, the computer looks up and dials the phone number for www.youtube.com for me automatically.

To get connected to www.youtube.com, Internet “routers” act like telephone operators and route the connection to the right server at www.youtube.com. Like telephone network switches, Internet routers connect the “call” automatically and while there may be many different ways to make the connection, the routers will select the best route based on a number of variables including the distance the connection covers, the speed of the connection, and so on.

Internet routers are intelligent in that they are able to share what routes are better than others with other routers. For example, if I were calling a phone number with the area code 705 and getting a noisy connection, I might need to be switched to a different connection to get a clear signal. Similarly, if my connection to www.youtube.com is poor, a better route may be required and Internet routers are able to share information about which route to a given server is the best.

And that’s how PieNet shut down YouTube. PieNet configured their Internet routers to appear to have a better route to www.youtube.com than other routers. Soon their routers shared this new and better route with other routers who in turn shared it with even more routers and soon the news was spreading like wildfire. The problem was, PieNet made sure that this hot new route to www.youtube.com actually led to PieNet’s own servers and not YouTube at all. Anyone trying to connect to www.youtube.com that was unfortunate enough to connect through an Internet router that had heard about the great new route were redirected to PieNet.

A remarkable side effect of PieNet’s actions was that most of Pakistan’s connection to the Internet slowed down drastically and will likely continue to be slow for a few days. YouTube is a very busy Internet site and using our phone analogy, it accepts a lot of calls. PieNet having routed those calls to itself, bogged down much of PieNet’s own ISP’s network.

The entire story, political, religious, and the censorship angle are also fascinating and here are some links to other stories about it:

http://slashdot.org/article.pl?sid=08/02/25/1322252

http://www.renesys.com/blog/2008/02/pakistan_hijacks_youtube_1.shtml

http://billso.com/2008/02/24/pakistan-blocks-youtube-breaks-trust

http://www.ethanzuckerman.com/blog/2008/02/25/how-a-pakistani-isp-briefly-shut-down-youtube