With the recent rise in anti-government protests in the Middle East, there has been renewed interest in the use of the Internet as a means of communication. Authoritarian governments, such as those in Egypt and Libya, have reacted by trying to shut down Internet service, or to sever connections with the outside world.
Last week’s issue of The Economist has an article on some of the methods that dissidents have used to circumvent these restrictions. Some of the techniques used, such as making directional antennas for cell phones from metal cans and other hardware, in order to extend their range considerably, have been used by do-it-yourself enthusiasts for some time. Others, like adapting satellite dishes to deliver wireless network connections over long distances, are relatively new.
Yahel Ben-David, an electrical engineer at the University of California, Berkeley, who has designed secret cross-border links to the internet for people in several countries, does so by adding standard USB dongles designed for home Wi-Fi networks. Thus equipped, two properly aligned dishes as much as 100km apart can transmit enough data to carry high quality video.
Techniques have also been worked out that can use satellite transmissions, ham radio, and portable “backpack” FM radio transmitters. One advantage of many of these techniques, particularly those that use directional transmissions, is that they are much harder for the authorities to track down than the omni-directional transmissions from more conventional setups.
Some of the more creative approaches even use conventional consumer products as covert radio transmitters.
Kenneth Geers, an American naval-intelligence analyst at a NATO cyberwar unit in Tallinn, Estonia, describes a curious microwave oven. Though still able to cook food, its microwaves (essentially, short radio waves) are modulated to encode information as though it were a normal radio transmitter.
From time to time, various idealistic folks have forecast a future in which the Internet would bring free and open communications to everyone. As with many idealistic predictions, reality has often refused to cooperate. But the proliferation of methods does make a difference, since a government that wants to censor information effectively has to control all channels, not just some. For those authoritarian regimes, it creates a situation a former colleague described (admittedly in a different context) as similar to “being attacked by ants”. You can step on a lot of them, but it’s awfully difficult to make sure none gets through.