BBC World Service
Iran has blocked many social networking sites and blogs
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.
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.
After that experience, Estonia established a body called the Cooperative Cyber Defence Centre of Excellence, in order to enhance Nato's cyber defence capability.
"A number of government websites, Estonian banks and media websites were brought down by a massive flood of artificial traffic, that was brought in from the outside, bringing down a number of websites over the course of a few weeks," he added.
The Estonian President, Toomas Hendrik Ilves has just returned from a brief tour of the United States where he met with President Obama in Washington to discuss cyber issues.
"Ultimately I would say that the attacks actually back-fired because Estonia had been talking about cyber-security for a variety of reasons, even telling Nato that we ought to have a cyber-centre of excellence," said President Ilves.
Nato agreed that it was a serious issue and the centre was set up in Estonia's capital city Tallinn.
One of the major issues in cyber warfare is defining what it actually means, thinks Mr Farivar.
What does cyber-war actually mean?
"After the Estonian attack there was a lot of rhetoric that was thrown around, cyber-war, digital pearl harbour, cyber 9/11, these kinds of hyperbolic phrases," he said.
"We need to be careful with how we describe these types of issues because when you talk about war, it has a very specific definition in a political and legal context.
"Should we invoke Article Five of the Nato Charter which says that an attack against one Nato country is an attack on all Nato countries and should all the Nato countries then attack back at some unknown entity through cyber means?" he asked.
The 2007 attacks in Estonia were launched via a botnet, a network of computers that have been subverted by malicious code so they fall under someone else's control.
At the conference, a couple of graduates from the University of Bonn in Germany showed off a technique they had developed to counter the effects of botnets.
Botnets are networks of computers which have been subverted by malicious code so they fall under someone else's control.
Owners of machines forming a botnet typically do not know their computer has been hijacked and home users account for 95% of all attacks mounted by botnets, according to figures from security firm Symantec.
"These two graduate students basically said, we now know how to counter-attack these botnets, we can undo them and use their own software against them.
"However, whilst they may want to launch their counter-attack against a botnet, they might want to counter these effects, as there are legal issues that they have to deal with first," said Mr Farivar
"The legal and political frameworks that exist around the world, haven't quite yet caught up to these technological realities," he added.
Digital Planet is broadcast on BBC World Service on Tuesday at 1232 GMT and repeated at 1632 GMT, 2032 GMT and on Wednesday at 0032 GMT.
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