[bbc] As protests and violence continue in Iran so do the attacks and counter-attacks online.
Pro-reform campaigners have targeted Iranian websites like that of President Ahmadinejad, while the state continues to clamp down on social networking sites, blogs and mobile networks in the country.
BBC World Service's technology programme, Digital Planet spoke to journalist Cyrus Farivar who recently attended the international conference on cyber warfare in Estonia.
"Over in Iran there has been a lot of activity ....trying to organise very crude cyber attacks to bring down the websites of opponents of the reformist candidate Mr Mousavi and to take down for example, the website of President Ahmadinejad, and other Iranian government websites as a way to protest against them.
"These types of attacks are a minor version of other types of cyber attacks that have been going on for many years around the world," he said.
President Barack Obama delivering remarks on securing the nation's cyber infrastructure
The Estonian President discussed cyber-war with US president
Estonia's own web infrastructure was blitzed from outside in 2007 and the attack was thought to have originated from Russia.
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