First systematic study maps 3,431 'airport' proxies used by half of Chinese circumvention users

A team of researchers from the University of Colorado Boulder, University of Washington, and other institutions has published the first systematic study of the 'airport' censorship circumvention ecosystem in China. The paper, titled 'Understanding the "Airport" Censorship Circumvention Ecosystem in China,' combines user surveys, social media analysis, and active network measurements to characterize these subscription-based proxy services. The researchers surveyed 1,667 Chinese internet users and found that airports are by far the most popular off-the-shelf circumvention tool, used by over half of respondents. Users primarily cite ease of use, performance, and access to geo-restricted services like ChatGPT and Netflix as motivators.

By scanning the internet and scraping Telegram announcement channels, the team identified 3,431 active airports, most built on a handful of open-source toolkits. They subscribed to 35 airports and characterized their performance, which often surpasses direct connections through the Great Firewall due to a distinctive multi-hop architecture. However, airports also pose new challenges: they accept payment through commercial services like Alipay, suffer frequent government takedowns, are difficult for users to configure optimally, and many deploy their own distinct censorship policies. The study concludes that airports are far more widely used than other circumvention tools from academic literature but introduce new forms of fragility and control, offering lessons for future circumvention research.