Syriaâs access to the Internet was cut on Tuesday. The most likely culprit, security researchers said, was the Syrian government.
Syrian Internet traffic came to a halt just before 3 p.m. Eastern time. Google reported a drop in Internet traffic around that time, as did the Local Coordinating Committees, an antigovernment activist group in Syria.
Four physical cables connect Syria to the Internet â" three under the sea, and the fourth over land through Turkey. For outsiders to cause Tuesdayâs outage, security experts say, they would have had to physically cut all four cables simultaneously.
That does not appear to have happened in this case, according to security experts. Instead, someone with access to the physical connections dropped the Border Gateway Protocol, or B.G.P., routes into Syria in such a way that any information trying to enter the country was not able to find its way.
âItâs akin to someone removing all the street signs into Syria,â said Matthew Prince, the founder of CloudFlare, an Internet security firm that distributes large volumes of traffic across the Internet. The firm put together a video illustrating Syriaâs outage.
The same technique was used to shut down the Internet and mobile phone service last November. Syrian government officials said terrorists, not the government, were responsible for that outage, but evidence pointed to government involvement.
Ironically, Syrian opposition groups are more immune to Internet and cellphone outages than ordinary Syrians. In Syriaâs opposition-controlled territories, rebels have successfully built an alternate system of Internet and cellphone connectivity using two-way satellite devices.
But experts warn that the use of satellite devices also makes it much easier for the Syrian government to track the rebelsâ location.
âRadio direction finding and signals intelligence could easily be deployed in this scenario to figure out where the opposition is communicating from,â said John Scott-Railton, a research fellow at the Citizen Lab, an organization at the University of Toronto that focuses on Internet security.