Understanding the "Airport" Censorship Circumvention Ecosystem in China
For researchers and policymakers studying censorship circumvention, this work reveals that a previously undocumented ecosystem (airports) dominates real-world usage, introducing new fragility and control mechanisms that challenge existing assumptions.
This paper presents the first systematic study of the 'airport' censorship circumvention ecosystem in China, finding that over half of 1,667 survey respondents use airports, which often outperform direct connections through the Great Firewall due to a multi-hop architecture. The study identifies 3,431 active airports and characterizes their performance, security risks, and government takedowns.
In China, a burgeoning underground market sells citizens subscription-based censorship circumvention proxies known as ''airports''. We present the first systematic study of this ecosystem, combining user surveys, social media analysis, and active network measurements. We find that airports are by far the most popular off-the-shelf censorship circumvention tool in China, used by over half of our 1,667~survey respondents, who cite their ease of use, performance, and access to geo-restricted services like ChatGPT and Netflix. By scanning the Internet and scraping Telegram announcement channels, we identify 3,431 active airports built on a handful of open-source toolkits. We subscribe to 35 airports and characterize their performance, which often surpasses direct connections through the Great Firewall due to a distinctive multi-hop architecture. However, airports also pose new challenges and security risks: they accept payment through commercial services like Alipay, suffer frequent government takedowns, and are difficult for clients to configure optimally. Many airports also deploy their own distinct censorship policies. Airports are far more widely used than other circumvention tools from the academic literature, but introduce new forms of fragility and control, offering both lessons and opportunities for future circumvention research.