Yesterday, something unprecedented happened: Egypt turned off the internet. A nation of 80,000,000 instantly disconnected. So how'd they do it?
Phone Calls
There was no giant lever or big red button involved, but in reality it was almost as easy: the Egyptian Government simply issued an order for ISPs to shut down service.
"Under Egyptian legislation the authorities have the right to issue such an order and we are obliged to comply with it," Vodafone Egypt explained in a statement shortly after. Along with Vodafone, Egypt's other three major ISPs, Link Egypt, Telecom Egypt, and Etisalat Misr, all stopped service. Jim Cowie, the co-founder and CTO of internet monitoring firm Renesys, told the WSJ:
What is most likely is that somebody in the government gives a phone call to a small number of people and says, ‘Turn it off.' And then one engineer at each service provider logs into the equipment and changes the configuration of how traffic should flow.
It was likely as easy as that.
BGPs
Renesys saw the effects immediately. Some 3,500 Border Gateway Protocol or BGP routes—the places where networks connect and announce which IP addresses they are responsible for—disappeared in an instant:
At 22:34 UTC (00:34am local time), Renesys observed the virtually simultaneous withdrawal of all routes to Egyptian networks in the Internet's global routing table. Approximately 3,500 individual BGP routes were withdrawn, leaving no valid paths by which the rest of the world could continue to exchange Internet traffic with Egypt's service providers. Virtually all of Egypt's Internet addresses are now unreachable, worldwide.