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.
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.
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.
Thanks! -- Sadia
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:
- 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.
- 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.
On Thu, Sep 25, 2014 at 12:47:49PM -0700, Sadia Afroz wrote:
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?
Before the pluggable transports era, we tried to make Tor's link handshake look like a Firefox talking to a Web server [0]. It turned out that it's quite difficult to mimic TLS handshakes and some countries became good at fingerprinting Tor's TLS handshake. Now that we have obfsproxy, the questions shifted from "how do we change Tor?" to "what additional pluggable transport do we need?".
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.
The wiki does not have a well-defined set of maintainers and is indeed starting to collect some dust. It's a community effort so please feel free to update it.
- 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.
Despite the spike caused by the botnet, it should still be possible to identify censorship events in the time series. Censorship systems would likely not care if they block a genuine Tor user or a bot---as long as they don't target a particular Tor version. As a result, I would still expect an effective censorship event to significantly reduce the total number of Tor users in a given country.
Let me know if there are other places I should look into to find censorship events.
Often, the help desk learns about censorship events first. However, there's also some noise in help desk tickets as it's not always easy to distinguish between network issues and country-wide censorship.
[0] https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/TLSHistory
Cheers, Philipp
Thanks! This has been very helpful.
Is there a way to get the help desk data? Is it available online?
On Mon, Sep 29, 2014 at 7:03 AM, Philipp Winter phw@nymity.ch wrote:
On Thu, Sep 25, 2014 at 12:47:49PM -0700, Sadia Afroz wrote:
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?
Before the pluggable transports era, we tried to make Tor's link handshake look like a Firefox talking to a Web server [0]. It turned out that it's quite difficult to mimic TLS handshakes and some countries became good at fingerprinting Tor's TLS handshake. Now that we have obfsproxy, the questions shifted from "how do we change Tor?" to "what additional pluggable transport do we need?".
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.
The wiki does not have a well-defined set of maintainers and is indeed starting to collect some dust. It's a community effort so please feel free to update it.
- 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.
Despite the spike caused by the botnet, it should still be possible to identify censorship events in the time series. Censorship systems would likely not care if they block a genuine Tor user or a bot---as long as they don't target a particular Tor version. As a result, I would still expect an effective censorship event to significantly reduce the total number of Tor users in a given country.
Let me know if there are other places I should look into to find
censorship
events.
Often, the help desk learns about censorship events first. However, there's also some noise in help desk tickets as it's not always easy to distinguish between network issues and country-wide censorship.
[0] https://trac.torproject.org/projects/tor/wiki/org/projects/Tor/TLSHistory
Cheers, Philipp
On Mon, Sep 29, 2014 at 01:30:48PM -0700, Sadia Afroz wrote:
Is there a way to get the help desk data? Is it available online?
Unfortunately, there's no way to share this data, so I shouldn't have brought it up, sorry. The usage statistics are probably more reliable anyway, so I would focus on the publicly available data.
By the way, there's also a trac component which is called "Censorship analysis" [0] which might contain some tickets you haven't found yet.
[0] https://trac.torproject.org/projects/tor/query?component=Censorship+analysis
Cheers, Philipp
Philipp Winter wrote:
On Mon, Sep 29, 2014 at 01:30:48PM -0700, Sadia Afroz wrote:
Is there a way to get the help desk data? Is it available online?
Unfortunately, there's no way to share this data, so I shouldn't have brought it up, sorry.
Well, checking the monthly reports [0] might help you get a gist on what's happening in help desk world. It includes some statistics on the number of tickets and articles used to reply to those tickets. But I don't think it's much reliable for this kind of research.
[0] https://lists.torproject.org/pipermail/tor-reports/2014-September/000634.htm...
Bests,
Thanks!
On Tue, Sep 30, 2014 at 8:52 AM, Philipp Winter phw@nymity.ch wrote:
On Mon, Sep 29, 2014 at 01:30:48PM -0700, Sadia Afroz wrote:
Is there a way to get the help desk data? Is it available online?
Unfortunately, there's no way to share this data, so I shouldn't have brought it up, sorry. The usage statistics are probably more reliable anyway, so I would focus on the publicly available data.
By the way, there's also a trac component which is called "Censorship analysis" [0] which might contain some tickets you haven't found yet.
[0] https://trac.torproject.org/projects/tor/query?component=Censorship+analysis
Cheers, Philipp
On Mon, Sep 29, 2014 at 10:03 AM, Philipp Winter phw@nymity.ch wrote:
It's a community effort so please feel free to update it.
The Wiki, rather than the git repository, seems like the most appropriate place for publicly-accessible documentation. I can commit to updating the Iran section in the next couple of days, including the most recent event.
-
Arturo Filastò -
Collin Anderson -
Nima Fatemi -
Philipp Winter -
Sadia Afroz