GFW Discussion



I previously commented on the Ignoring the “Great Firewall of China” paper but 0day pointed me to a good critique of the paper. The critique makes several points on the technical side including noting that circumventing keyword by blocking RST packets would not work for “‘hard’ IP filtering”, that China could upgrade its system to account for other noted deficiencies and that ignoring reset packets is detectable and has security concerns.

The author notes that it not all just about technical measures:

But, based on what we’ve learned about how they’ve worked, and what the industry (and, therefore, the PRC) knows about content filtering, let me take a wild guess: the Chinese don’t particularly care that it’s possible to evade their filters. They care about perception.

However, it is not just a perception of the effectiveness (in technical terms) of their filtering that China is concerned about it is the perception of acceptable and unacceptable content among the population. Filtering is a mechanism to convey the range of acceptable discussion in order to re-enforce self-censorship. Filtering does not have to be technically foolproof, the reality is that *most* people won’t even try to access banned content let alone attempt to circumvent filtering.

There is this perception that if you visit a blocked site or use a circumvention system that the internet police will be at your door in “real time”, but that’s just not the case. Many people use open, plaintext proxies for circumvention and many sites with “sensitive” content are not blocked. The IP addresses of circumvention systems are known, occasionally China acts to disrupt known circumvention systems. Arrests and so forth appear to only be used against those who disseminate (rather than just simply access) “sensitive” information. There will always be risks to the end-user of circumvention technology. For providers, the goal is to make is a safe as possible and to fully inform the users of the risks.

However, I disagree with the statement that the paper will lead to China improving their filtering system. China is *always* improving its filtering technology and introducing measures (or getting companies to censor themselves) at different levels of access. The technical analysis in the paper is a good step towards further understanding the GFW, what type of technology is being used, and helps inform the development of circumvention technology.

2 comments.

  1. […] GFW Discussion […]

  2. […] I think there are many folks who disagree, finding that the Great Firewall in China is doing quite an effective job of filtering. As Nart Villeneuve of Citizen Lab said recently: Filtering does not have to be technically foolproof, the reality is that *most* people won’t even try to access banned content let alone attempt to circumvent filtering. […]

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