Mr. Cowie noted that the shutdown in Egypt did not appear to have diminished the protests — if anything, it inflamed them — and that it would cost untold millions of dollars in lost business and investor confidence in the country. But he added that, inevitably, some autocrats would conclude that Mr. Mubarak had simply waited too long to bring down the curtain.
“Probably there are people who will look at this and say, it really worked pretty well, he just blew the timing,” Mr. Cowie said.
Speaking of the Egyptian shutdown and the earlier experience in Tunisia, whose censorship methods were less comprehensive, a senior State Department official said that “governments will draw different conclusions.”
“Some may take measures to tighten communications networks,” said the official, speaking on the condition of anonymity. “Others may conclude that these things are woven so deeply into the culture and commerce of their country that they interfere at their peril. Regardless, it is certainly being widely discussed in the Middle East and North Africa.”
Vulnerable Choke Points
In Egypt, where the government still has not explained how the Internet was taken down, engineers across the country are putting together clues from their own observations to understand what happened this time, and to find out whether a future cutoff could be circumvented on a much wider scale than it was when Mr. Mubarak set his attack in motion.
The strength of the Internet is that it has no single point of failure, in contrast to more centralized networks like the traditional telephone network. The routing of each data packet is handled by a web of computers known as routers, so that in principle each packet might take a different route. The complete message or document is then reassembled at the receiving end.
Yet despite this decentralized design, the reality is that most traffic passes through vast centralized exchanges — potential choke points that allow many nations to monitor, filter or in dire cases completely stop the flow of Internet data.
China, for example, has built an elaborate national filtering system known as the Golden Shield Project, and in 2009 it shut down cellphone and Internet service amid unrest in the Muslim region of Xinjiang. Nepal’s government briefly disconnected from the Internet in the face of civil unrest in 2005, and so did Myanmar’s government in 2007.
But until Jan. 28 in Egypt, no country had revealed that control of those choke points could allow the government to shut down the Internet almost entirely.
There has been intense debate both inside and outside Egypt on whether the cutoff at 26 Ramses Street was accomplished by surgically tampering with the software mechanism that defines how networks at the core of the Internet communicate with one another, or by a blunt approach: simply cutting off the power to the router computers that connect Egypt to the outside world.
But either way, the international portals were shut, and the domestic system reeled from the blow.
The Lines Go Dead
The first hints of the blackout had actually emerged the day before, Jan. 27, as opposition leaders prepared for a “Friday of anger,” with huge demonstrations expected. Ahmed ElShabrawy, who runs a company called EgyptNetwork, noticed that the government had begun blocking individual sites like Facebook and Twitter.