Abstract:
The Great Firewall of Iran (GFI) has evolved significantly over the past decade,
constantly adding sophisticated blocking techniques. Prior research into Iran’s
Internet censorship, however, has primarily been one-off studies, leaving
significant gaps in understanding the breadth and evolution of its filtering
strategies. Exploiting the bidirectional blocking behaviors of the GFI and its
own injection mechanisms as a side-channel to determine traffic disruption, we
developed IRBlock, a novel large-scale, multi-protocol measurement system
designed to measure DNS, HTTP, and UDP-based censorship across Iran, enabling
continuous monitoring and in-depth exploration of the GFI’s blocking behavior.
