On Aug 15, 2012, at 2:46 AM, "Eric S Johnson" <crates at oneotaslopes.org> wrote:
There are persistent reports that China?s cybercensorship can sometimes vary (a little) by ISP, but I?ve never seen this (I?ve only been to ~13 of the 34 PRC-defined provinces), and Alkasir hasn?t ever detected any such variations.
I carried out a few experiments last year, looking at regional variations in the responses of Chinese DNS servers for domains that had been reported as blocked by Herdict. (Using a list of DNS servers pulled from the APNIC WHOIS database.) There are plenty of caveats to the approach I took: DNS server location doesn't map reliably onto where the user is, DNS poisoning can occur at border routers, DNS servers can return different responses to different people, my methods for detecting poisoning were quite crude, etc. Given all that, I found a lot of variation in the DNS responses across China. I published a paper about it in FOCI'11 last year, but that mainly focused on the ethical issues of censorship research: http://static.usenix.org/events/foci11/tech/final_files/Wright.pdf There are some preliminary results and visualisations in this presentation: http://www.slideshare.net/josswright/finegrained-censorship-mapping (Apologies for my terrible GIS skills...) The approach was quite crude, but does support the hypothesis of filtering being at least partially decentralised. (Which makes sense for such a massive project.) I'm currently looking at quite a promising approach for a much more interesting set of experiments based on IP scans rather than DNS. Watch this space. :) Joss _______________________________________________ liberationtech mailing list liberationtech@lists.stanford.edu Should you need to change your subscription options, please go to: https://mailman.stanford.edu/mailman/listinfo/liberationtech If you would like to receive a daily digest, click "yes" (once you click above) next to "would you like to receive list mail batched in a daily digest?" You will need the user name and password you receive from the list moderator in monthly reminders. You may ask for a reminder here: https://mailman.stanford.edu/mailman/listinfo/liberationtech Should you need immediate assistance, please contact the list moderator. Please don't forget to follow us on http://twitter.com/#!/Liberationtech ----- End forwarded message ----- -- Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org ______________________________________________________________ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE