the site at the same time . The same error would be caused by a so-called `` denial of service '' attack -- using a program to flood a site with thousands of hits in a short time . Access to networking sites such as Facebook and Twitter and photography site Flickr have been blocked in Iran , where the government also has been accused of blocking text-messaging , launching denial of service attacks and spreading misinformation to protest communities online . Watch CNN 's Octavia Nasr explain how voices of dissent are getting out '' But Web users have been able to get around those roadblocks by the thousands , thanks to Internet proxies -- Web servers set up in other countries that allow Iranians to hide their computer 's Internet Protocol address from censors within the country . `` I think the filters and the restrictions have been going on for so long in Iran that the experienced people are already prepared for this , '' said Jon Pincus , a former Microsoft project manager and digital activist who works on projects promoting online freedom . The networking sites have been crucial in sharing information among protesters .
-LRB- CNN -RRB- -- It 's a high-tech , high-stakes game of cat-and-mouse . Ryan Kelly , a Web designer from London , England , says his software was used to attack an Iranian Web site . As the Iranian government seeks to crack down on the online networks being used by protesters who question the nation 's election results , a community of Net-savvy users -- both inside and outside the country -- are working to try to stay one step ahead . `` To the Iranian government hackers who keep attacking the places they see as a threat , you are wasting your time , '' wrote one anonymous poster to a message board loaded with eyewitness accounts of violence , plans for protests and notices about people reported missing or dead . `` You are completely outnumbered . There are thousands of Iranians who want to be free and people who support them for every one of you there is . '' That site , with a server in California , was unable to be accessed for a couple of hours Wednesday afternoon . The error could have been caused by too many people trying to access