WCMT: Web censorship monitoring tool

Internet Censorship detection: A survey

“…The "Web Censorship Monitoring Tool" as presented by Esnaashari et al [52] consists of two different architectures, one devoted to detection of HTTP tampering and the other to detection of a port-based filtering (a subset of IP/port filtering). Despite the preliminary nature of the work, the paper proposes an interesting variation on the detection of HTTP tampering.…”

How India Censors the Web

“…Due to the size of our corpus, we cannot rely on manual inspection as done by [47]. Existing automated techniques for detecting censored HTTP responses usually rely on making comparisons with uncensored responses, collected either via control servers set up in censorship-free countries [7,42], or via Tor circuits [18,19,45,47]. Due to the dynamic nature of content hosted on websites, comparing verbatim responses can be erroneous [28].…”

“…They report that comparing a test response's length and HTML DOM structure with that of an uncensored response can help identify such pages with a high accuracy. Similarly, other authors use response length in conjunction with different HTML similarity metrics for comparisons [7,18,19]. However, these approaches perform well only in instances where censors explicitly inject censorship notices, an assumption that generally doesn't hold true: as discussed above, censors have been known to adopt tacit approaches such as responding with HTTP errors or redirections.…”

“…This is done via 5 control servers in censorshipfree countries (US, CA, GB, NE and AU), and via the test network. Unlike some studies [18,19,45,47] we avoid using Tor circuits for collecting control responses, since some websites blacklist them and respond differently to HTTP requests originating from them. Additionally, instead of using just one control response [19,28,47], we consider multiple responses.…”