[tor-bugs] #8710 [Tor]: Sybil selection should prefer measured over advertised bw

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#8710: Sybil selection should prefer measured over advertised bw
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 Reporter:  nickm                    |          Owner:                    
     Type:  defect                   |         Status:  needs_review      
 Priority:  normal                   |      Milestone:  Tor: 0.2.4.x-final
Component:  Tor                      |        Version:                    
 Keywords:  tor-auth 024-deferrable  |         Parent:                    
   Points:                           |   Actualpoints:                    
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Changes (by nickm):

  * keywords:  tor-auth => tor-auth 024-deferrable


Comment:

 > What security-related attacks are we worried about here? "We could end
 up picking a relay with lower measured bandwidth" is the failure mode that
 I see?

 Well, the current behavior lets the sybil-attacker pick which node they
 would like to have appear in the consensus.  It also destabilizes the
 consensus if the nodes' measured values are less than their advertised
 values, since as soon as a new node shows up, it will seem preferable to
 all measured nodes.

 These don't seem immediately exploitable in any scary way, but I'm not
 comfortable leaving in calculations that lead to our making decisions
 based on advertised bandwidth. It doesn't have a great track record.

 This isn't to say we don't want a solution for #8163 , but rather that
 leaving this ticket unfixed is not the solution for #8163.

 I guess we could defer this to 0.2.5 along with #8163?

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/8710#comment:5>
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