Chinese attackers made use of the "Great Cannon," the offensive Great Firewall sister-system to launch the recent service attacks denials targeting GreatFire.org, the anticensorship site and GitHub, a code repository.
The first DDoS set of attacks happened on March 16, hitting the GreatFire.org. With the attack, GitHub became the unintentional victim because another DDoS smashed it offline, the Threat Post revealed. It has been widely believed that the attacks were launched in an aim of shutting down services that target China's content blocking, massive infrastructure more popularly known as the "Great Firewall."
The Global Affairs' Citizen Laboratory of the University of Toronto's Munk School, Princeton University, Berkeley's University of California, and the International Computer Science Institute started to monitor the attacks quietly on March 18 until April 8.
The Great Firewall of China does not actually operate as a barrier platform. Instead, it is a system that monitors connections that occur between the mother country and the worldwide Internet for all banned contents, which are blocked by injecting fraudulent copies of TCP reset packets. The packets cause both the recipient and the sender's communications to halt, eventually blocking banned traffic.
The Citizen Lab published on its site, "On-path systems have architectural advantages for censorship, but are less flexible and stealthy than in-path systems as attack tools, because while they can inject additional packets, they cannot prevent in-flight packets (packets that have already been sent) from reaching their destination. One could generally determine the existence of an on-path system through observing the anomalies that resulted due to the presence of both legitimate and injected traffic."