How Did Syria Turn Off The Internet... And What Other Countries Can Just Hit The Off Switch Like That?
To begin, all connectivity to Syria, not just some regions, has been cut. The exclusive provider of Internet access in Syria is the state-run Syrian Telecommunications Establishment. Their network AS number is AS29386. The following network providers typically provide connectivity from Syria to the rest of the Internet: PCCW and Turk Telekom as the primary providers with Telecom Italia and TATA for additional capacity. When the outage happened, the BGP routes to Syrian IP space were all simultaneously withdrawn from all of Syria's upstream providers. The effect of this is that networks were unable to route traffic to Syrian IP space, effectively cutting the country off the Internet.
Syria has 4 physical cables that connect it to the rest of the Internet. Three are undersea cables that land in the city of Tartous, Syria. The fourth is an over-land cable through Turkey. In order for a whole-country outage, all four of these cables would have had to been cut simultaneously. That is unlikely to have happened.
Furthermore, they note that the shutdown was quite systematic, suggesting "this was done through updates in router configurations, not through a physical failure or cable cut."
Meanwhile, the folks at Renesys look into just how difficult it is to cut a country off from the internet, and whether other countries are at risk of the same sort of thing. Basically, it comes down to how decentralized the internet is in various countries -- and in many countries there isn't much decentralization. As Renesys notes, some countries have just one or two telcos who handle all internet traffic to and from the world. Those countries are easy to cut off. Renesys helpfully provides a map:
They then go into more details. Here are the two bullet points on the more at risk countries. If you want to learn about the somewhat more safe countries, click on over and read their full post (which has a much bigger discussion on all of this, which I highly recommend):
If you have only 1 or 2 companies at your international frontier, we classify your country as being at severe risk of Internet disconnection. Those 61 countries include places like Syria, Tunisia, Algeria, Turkmenistan, Libya, Ethiopia, Uzbekistan, Myanmar, and Yemen.
If you have fewer than 10 service providers at your international frontier, your country is probably exposed to some significant risk of Internet disconnection. Ten providers also seems to be the threshold below which one finds significant additional risks from infrastructure sharing — there may be a single cable, or a single physical-layer provider who actually owns most of the infrastructure on which the various providers offer their services. In this category, we place 72 countries, including Oman, Benin, Botswana, Rwanda, Pakistan, Kyrgyzstan, Uganda, Armenia, and Iran. Disconnection wouldn't be trivial, but it wouldn't be all that difficult. Egypt falls into this category as well; it took the Mubarak government several days to hunt down and kill the last connections, but in the end, the blackout succeeded.
As the internet is increasingly a global phenomenon, this kind of stuff matters a lot.Permalink | Comments | Email This Story
Read the full story here.