Custom blocking tools have replaced brute-force shutdowns.
View of the skyline in Tehran, Iran on Saturday, Aug. 18, 2007. Educated, ambitious and connected to the outside world by the Internet, under-30s make up two-thirds of Iran's 70 million people and want President Mahmoud Ahmadinejad to come good on his promises to tackle unemployment and make "marriage and housing'' his government's priority. Photographer: Abbas Kowsari/Bloomberg News