[ooni-dev] Complete list of Tor blocking events

[Arturo Filastò]

On 9/25/14, 9:47 PM, Sadia Afroz wrote:
> Hi all,
> I am trying find a list of events when different countries blocked Tor
> to understand why and how those countries blocked it and how Tor
> resolved those issues. Do you know if anybody is maintaining such a list?
> I found censorshipwiki
> (https://trac.torproject.org/projects/tor/wiki/doc/OONI/censorshipwiki)
> that has a similar list. But it seems that it's not maintained any more
> as it doesn't have the recent blocking incident by Iran. Also I'm not
> sure how comprehensive is this list as it's missing Tunisia. 
> 

Hi Sadia,

Yes you are right, that list is not much up to date. For some other,
also not much up to date, information you may also want to look at:

https://gitweb.torproject.org/censorship-timeline.git

It contains packet dumps blocked in ethiopia and kazakhstan.

> Do you have any suggestion on how to create a comprehensive list of Tor
> blocking by countries? 
> 
> My colleagues and I were thinking of two ways to go about this:
> 
> 1. Get the total number of Tor users from every countries over time and
> look for anomalous fluctuations. When we created such a graph we noticed
> that huge number of bot controlled nodes that appear in almost every
> country's graph. It seems hard to identify real censorship events from
> graphs like this that can be affected by other events unrelated to
> censorship.
> 

On this topic you may be interested in reading this paper:
https://research.torproject.org/techreports/detector-2011-09-09.pdf

It explains a method for detecting censorship of Tor based on metrics.
At the time of writing it though, we didn't have the botnet problem, so
I see how it can be a bit more complicated to do now.

> 2. Search for tickets on https://trac.torproject.org/projects/tor
> <https://trac.torproject.org/projects/tor/ticket/12727> with keywords
> related to censorship, for example "censorship", "block", "dpi". This
> has the potential problem of missing many events where nobody complained
> or filed a bug report with different keywords.
> 
> Let me know if there are other places I should look into to find
> censorship events.

I am adding also Philip Winter to cc that may know of other resources to
use to get good data on censorship events related to Tor.


~ Art.