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

[Tor Bug Tracker & Wiki]

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

Comment (by dgoulet):

 It seems clear here that we can't stop a network scan to finally succeed
 whatever behavior so our best course of actions is to slow down and made
 it as hard as we can for the attacker to scan.

 Option '5' scares me a bit in terms of added overhead. Seems like adding
 delay to the bad circuit opens the door to some DoS for which an attacker
 could just open 65534 circuits to the HS with the wrong port and those
 circuits would stay open for an unknown amount of time?... If that would
 be acceptable for some reasons, adding a random delay before sending back
 the reason will also slow down quite a bit the scanner :).

 I would go for sending back END_STREAM_REASON_DONE (application closed the
 connection) and DROP the circuit after.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13667#comment:8>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online