Measuring QUIC Censorship in Understudied Regions

This thesis examines application-layer Internet censorship targeting the QUIC protocol, focusing on how certain networks interfere with QUIC traffic while allowing traditional TCP/TLS communication. After conducting an extensive literature review on Internet censorship techniques and QUIC’s design characteristics, a list of verified QUIC-supported domains was compiled using a Swiss vantage point as a censorship-free baseline. A modular probing tool was then developed using the aioquic library to perform controlled QUIC and TCP/TLS handshakes. The tool was deployed across multiple Virtual Private Servers (VPSs) located in South and Southeast Asia to detect region-specific blocking. Each probe recorded detailed handshake outcomes, success codes, and error traces to identify cases where QUIC connections failed but TCP succeeded, indicating potential application-layer interference. The analyzed results show clear evidence of QUIC-specific blocking in some networks, whereas others demonstrated normal connectivity or general network-layer disruptions. The study concludes that while QUIC remains accessible in most tested regions, selective filtering of QUIC traffic persists, highlighting evolving censorship practices as encrypted, UDP-based protocols become more widespread.