How Egypt Switched Off The Internet
Its an astonishing move, and one that seems almost unimaginable for a nation that not only has a relatively strong internet economy but also relies on its connections to the rest of the world.
But how did the government actually do it? Is there a big kill switch inside Egyptian President Hosni Mubaraks office? Do physical cables have to be destroyed? Can a lockdown like this work?
Plenty of nations place limitations on communications, sometimes very severe ones. But there are only a few examples of regimes shutting down communications entirely Burmas military leaders notably cut connectivity during the protests of 2007, and Nepal did a similar thing after the king took control of the government in 2005 as part of his battle against insurgents. Local Chinese authorities have also conducted similar, short-lived blockades.
The OpenNet Initiative has outlined two methods by which most nations could enact such shutdowns. Essentially officials can either simply close down the routers which direct traffic over the border hermetically sealing the country from outsiders or go further down the chain and switch off routers at individual ISPs to prevent access for most users inside.
In its report on the Burmese crackdown, ONI suggests that the junta used the second option, something made easier because it owns the only two internet service providers in the country.
The Burmese Autonomous System (AS), which, like any other AS, is composed of several hierarchies of routers and provides the Internet infrastructure in-country. A switch off could therefore be conducted at the top by shutting off the border router(s), or a bottom up approach could be followed by first shutting down routers located a few hops deeper inside the AS.
A high-level traffic analysis of the logs of NTP (Network Time Protocol) servers indicates that the border routers corresponding to the two ISPs were not turned off suddenly. Rather, our analysis indicates that this was a gradual process.
While things arent clear yet, this doesnt look like the pattern seen in Egypt, where the first indications of internet censorship came earlier this week with the blockades against Twitter and Facebook but when access disappeared, it disappeared fast, with 90 percent of connections dropping in an instant.
Analysis by Renesys, an internet monitoring body, indicates that the shutdown across the nations major Internet service providers was at precisely the same time, 12:34am local time:
Renesys observed the virtually simultaneous withdrawal of all routes to Egyptian networks in the Internets global routing table The Egyptian governments actions tonight have essentially wiped their country from the global map.
Instead, the signs are that the Egyptian authorities have taken a very careful and well-planned method to screen off internet addresses at every level, from users inside the country trying to get out and from the rest of the world trying to get in.
It looks like theyre taking acti! on at tw o levels, Rik Ferguson of Trend Micro told me. First at the DNS level, so any attempt to resolve any address in .eg will fail but also, in case youre trying to get directly to an address, they are also using the Border Gateway Protocol, the system through which ISPs advertise their internet protocol addresses to the network. Many ISPs have basically stopped advertising any internet addresses at all.
Essentially were talking about a system that no longer knows where anything is. Outsiders cant find Egyptian websites, and insiders cant find anything at all. Its as if the postal system suddenly erased every address inside America and forgot that it was even called America in the first place.
A complete border shutdown might have been easier, but Egypt has made sure that there should be no downstream impact, no loss of traffic in countries further down the cables. That will ease the diplomatic and economic pressure from other nations, and make it harder for protesters inside the country to get information in and out.
Ferguson suggests that, if nothing else, the methods used by the Egyptian government proves how fragile digital communication really is.
What struck me most is that weve been extolling the virtues of the internet for democracy and free speech, but an incident like this demonstrates how easy it is particularly in a country where theres a high level of governmental control to just switch this access off.
Photograph used under Creative Commons license courtesy of Flickr user Muhammed Ghafari
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