[tor-bugs] #4581 [Tor]: Dir auths should defend themselves from too many begindir requests per address

[Tor Bug Tracker & Wiki]

#4581: Dir auths should defend themselves from too many begindir requests per
address
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     Reporter:  arma     |      Owner:  andrea
         Type:  defect   |     Status:  assigned
     Priority:  major    |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor      |    Version:  Tor: 0.2.7
   Resolution:           |   Keywords:  maybe-proposal, tor-auth,
Actual Points:           |  027-triaged-1-in, SponsorU
       Points:  medium   |  Parent ID:
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Comment (by andrea):

 So, I think the right place to add this check is in
 connection_exit_connect_dir() or immediately up its call chain.  It's easy
 enough to make this fail on the basis of some criterion, but I believe
 it's possible for these to occur either from a single-hop circuit (we know
 the client's real IP) or anonymized, in which case perhaps the criterion
 should be begindirs from the same circuit rather than the same IP so the
 would-be attacker at least must work.  Thoughts on the right filter to
 implement, anyone?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4581#comment:14>
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