[tor-bugs] #21394 [Core Tor/Tor]: connection timeouts are affecting Tor Browser usability

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Oct 26 07:01:57 UTC 2017


#21394: connection timeouts are affecting Tor Browser usability
-------------------------------------------------+-------------------------
 Reporter:  arthuredelstein                      |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Very High                            |      Milestone:  Tor:
                                                 |  0.3.2.x-final
Component:  Core Tor/Tor                         |        Version:
 Severity:  Normal                               |     Resolution:
 Keywords:  tbb-performance, tbb-usability,      |  Actual Points:
  performance, tbb-needs                         |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Comment (by teor):

 Replying to [comment:20 arthuredelstein]:
 > I did some more experiments:
 >
 > ...
 > Indeed I got 9/50 timeouts for the domain with http or https, but no
 timeouts for IPv4 and only a single timeout for IPv6.
 >
 > Does this ring any bells for Tor core experts? What might be happening
 with DNS here?

 Some exits may be overloading their resolvers. Or our code may be buggy.
 It would be helpful to identify the particular exits that are experiencing
 these timeouts, and work out if they are in the same AS or using the same
 resolvers.

 I also wonder if we should ask bandwidth authorities to use DNS whenever
 possible, so they see DNS timeouts, and downgrade exits that have them.
 See #24010.

 > Again I think the multiple timeouts are a little suspicious, and I don't
 quite understand how that jibes with it being a (pure) exit node problem.

 The only node in a tor path that uses DNS is an exit, so if DNS breaks, it
 causes issues at the exit.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/21394#comment:22>
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