[tor-bugs] #29279 [Circumvention/Obfs4]: Test obfs4 reachability

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#29279: Test obfs4 reachability
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 Reporter:  cohosh                               |          Owner:  cohosh
     Type:  task                                 |         Status:
                                                 |  needs_review
 Priority:  Very High                            |      Milestone:
Component:  Circumvention/Obfs4                  |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  NGO, community, anti-censorship-     |  Actual Points:
  roadmap                                        |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
                                                 |  Sponsor28-must
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Comment (by phw):

 Replying to [comment:21 cohosh]:
 > After about 2 months it looks like all private obfs4 bridges are still
 reachable (although there are a few times when they weren't able to fully
 bootstrap).
 >
 > Do we want to keep running these tests? I'd propose stopping these tests
 and maybe redesigned another one as mentioned above to look at how quickly
 blocking happens for different partitions of bridgedb.
 [[br]]
 I think we are good for now. Here's a summary of what we learned in this
 ticket. Please correct me if I got anything wrong:
 * We used a vantage point in China to continuously test several obfs4
 bridges.
 * We tested ndnop3 and ndnop4, which are
 [https://trac.torproject.org/projects/tor/wiki/doc/TorBrowser/DefaultBridges
 default bridges] and therefore effectively public. Unsurprisingly, we
 found these two bridges blocked in China.
 * We also set up private bridges that weren't supposed to be distributed
 over BridgeDB. These private bridges remained reachable throughout the
 experiment.
 * We can conclude from our results that the GFW is unable (or at least
 unwilling) to block an obfs4 bridge by just witnessing a client in China
 talk to a bridge outside of China.

 I filed #30872 to coordinate an experiment to test if China has broken any
 of BridgeDB's distribution channels.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29279#comment:23>
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