[tor-bugs] #25347 [Core Tor/Tor]: Tor keeps on trying the same overloaded guard over and over

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#25347: Tor keeps on trying the same overloaded guard over and over
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 Reporter:  teor                                 |          Owner:  asn
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.0.6
 Severity:  Normal                               |     Resolution:
 Keywords:  031-backport, 032-backport,          |  Actual Points:
  033-must, tor-guard, tor-client, tbb-          |
  usability-website, tbb-needs,                  |
  033-triage-20180320, 033-included-20180320     |
Parent ID:  #21969                               |         Points:  1
 Reviewer:                                       |        Sponsor:
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Comment (by mikeperry):

 If this behavior is infrequent, then it is probably a good idea not to
 rotate guards unless we get a *lot* of destroys.

 I don't like the fact that by not doing anything about this, we're
 allowing a confirmation/search attack where an adversary can DoS guards
 until a hidden service becomes (mostly) unreachable, and I would argue
 that such an attack is worse than moving to a different guard, but that
 attack could also be mitigated by just having two guards instead of one
 (since it is harder to keep pairs of guards offline simultaneously during
 a search for such a confirmation).

 So I accept the NACK of the patch (and the second commit in #25705), but I
 think we should not forget what this decision means wrt DoS and
 confirmation.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25347#comment:33>
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