[tor-bugs] #13667 [Tor]: Prevent port scanning of hidden services

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#13667: Prevent port scanning of hidden services
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     Reporter:  arma    |      Owner:
         Type:  defect  |     Status:  needs_review
     Priority:  major   |  Milestone:  Tor: 0.2.6.x-final
    Component:  Tor     |    Version:
   Resolution:          |   Keywords:  SponsorR tor-hs 025-backport
Actual Points:          |  Parent ID:
       Points:          |
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Comment (by dgoulet):

 After an IRC dicussion, the current solution is a bit weak because now a
 REASON_DONE + Killing circuit basically means an EXIT_POLICY reason which
 apart from adding some delay to the port scanning (attacker needs to open
 lots of circuit), it doesn't do much.

 nickm came up with an interesting idea.
 {{{
 < nickm> yeah.  If we really want to be sneaky, the way to do it is...
 < nickm> have a flag on the circuit that means "say DONE to everything".
 < nickm> Set that flag when we would otherwise send EXITPOLICY
 < nickm> Then refuse all connections on that circuit
 < nickm> This forces them to open 65535 circuits  to do a portscan, *and*
 doesn't leak down vs exitpolicy
 }}}

 I tend to like that.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13667#comment:20>
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