TWC: Phase: Small: Censorship Counterstrike via Measurement, Filtering, Evasion, and Protocol Enhancement

本项目研究当今一些民族国家的互联网审查制度。这项工作强调分析审查者执行审查时使用的技术措施，他们的操作造成附带损害的程度（意外封锁，或封锁完全在审查国之外的活动），以及由于审查运作方式的具体细节而造成的脆弱性。对于后者，我们分析了审查监控如何检测特定网络流量以抑制的缺陷，或者监视器如何试图阻止或破坏目标流量。这方面的研究侧重于窃听网络链路的监控形式，分析传输流量的副本，然后注入伪造的流量，看似从一个通信端点发送到另一个通信端点，指示另一方停止通信。这种“在路径上”的监控受到许多潜在的操纵和逃避，因为监控者对通信的看法与通信双方实际看到的不准确。我们特别致力于开发工具和改变互联网技术，以抵御这些形式的破坏，从而使用户能够自由访问互联网。

This project studies Internet censorship as practiced by some of today's nation-states. The effort emphasizes analyzing the techncial measures used by censors to perform censorship, the extent to which their operations inflict collateral damage (unintended blocking, or blocking of activity wholly outside the censoring nation), and vulnerabilities due to the specifics of how censorship operates. Regarding this latter, we analyze flaws in either how the censorship monitoring detects particular network traffic to suppress, or in how the monitor then attempts to block or disrupt the target traffic. This facet of the research focuses on forms of monitoring that eavesdrop on network links, analyze copies of transmitted traffic, and then inject forged traffic, seemingly sent from one of the communication endpoints to the other, instructing the other party to cease communication. Such "on-path" monitoring is subject to a number of potential manipulations and evasions due to the inexact view the monitor has of the comunication as actually seen by the communicating parties. We in particular then work towards developing tools and changes to Internet technology that can resist these forms of disruption and thus enable users to access the Internet freely.