Hackers launched a sustained attack against pro-democracy website Viet Tan on 13 August in a denial-of-service (DDoS) operation. Of the 77,000 IP addresses employed, 73 per cent originated from Vietnam. The Hanoi government’s firewall on www.viettan.org was lifted so that the network relying on computers from the country could take down the site. Viet Tan has been constantly blocked by Vietnamese censors, with web users in the country requiring proxies or other circumvention tools to access the site.