[tor-bugs] #13155 [Tor]: I can use an extend cell to remotely determine whether two relays have a connection open

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#13155: I can use an extend cell to remotely determine whether two relays have a
connection open
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     Reporter:  arma    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  normal  |  Milestone:  Tor: 0.2.???
    Component:  Tor     |    Version:
   Resolution:          |   Keywords:
Actual Points:          |  Parent ID:
       Points:          |
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Comment (by cypherpunks):

 This bug is not about port only, if any open channel for requested digest
 is canonical then no matter address or port. Relays prefer canonical
 connection, for most cases they connected in between using canonical
 connection, or no any connection in between installed yet. Attacker can to
 send extend request for scanning digest with controllable addresses as
 target. No timings for attack need, 99% of determinism.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13155#comment:5>
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