The Great Firewall of China (GFW) is one of, if not arguably the most advanced Internet censorship systems in the world. Because repressive governments generally do not simply publish their censorship rules, the task of determining exactly what is and isn’t allowed falls upon the censorship measurement community, who run experiments over censored networks. In this talk, we’ll discuss two ways censorship measurement has evolved from passive experimentation to active attacks against the Great Firewall.