China’s Internet censorship is a far cry from “building a great wall to prevent exchanges” from technical means. The use of “翻墙” will give people misunderstandings, and in fact legalized the silent “illegal intrusion of computer information systems” by the Chinese government.
Let us look at how the “blocking of specific websites” works in China’s Internet censorship.
DNS pollution
The 1st and 2nd fake DNS packet arrived earlier. Photo by Nick Cao
In this process, the distributed malicious nodes launch attacks on Internet users/DNS servers to answer their DNS queries.
RST
During this process, malicious nodes interfere with the TCP connection with a specific network address.
Routing black hole
In this process, the administrator of the audit system interferes with the order of the Internet and establishes a black hole router/AS. [1]And through the border routing protocol to direct network traffic to these black holes.
Deep Packet Inspection
This process involves cracking the unencrypted HTTP packet sent by the Internet user’s machine, which is an attack.
The above three methods are all “illegal intrusion into computer information systems,” and they are the same as those used by attackers.
[1] 刘刚, 云晓春, 方滨兴, 胡铭曾. “一种基于路由扩散的大规模网络控管方法”. 通信学报, 24(10): 159-164. 2003.