[tor-bugs] #15935 [Tor]: Implement a kill switch / exponential backoff for old clients

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#15935: Implement a kill switch / exponential backoff for old clients
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     Reporter:  teor    |      Owner:
         Type:  defect  |     Status:  new
     Priority:  normal  |  Milestone:  Tor: 0.2.7.x-final
    Component:  Tor     |    Version:  Tor: unspecified
   Resolution:          |   Keywords:  SponsorS, SponsorU needs-proposal
Actual Points:          |  Parent ID:  #15233
       Points:          |
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Changes (by nickm):

 * keywords:  SponsorS, SponsorU => SponsorS, SponsorU needs-proposal


Comment:

 Some random thoughts, some of which may be good:

 I know Roger has been very leery of anything like a version-based "kill
 switch" in the past (possibly out of a worry that it would make people
 worried that we were going to use it for evil). But that doesn't mean that
 the idea is hopeless.

 We used to have something a little like this, by the way.  That's how
 "recommended versions" used to work, I think.

 I  like the random exponential backoff idea; it should probably be a
 separate ticket though.

 Perhaps this kind of thing should always be advisory.  For example, there
 could be a way to disable it at compile-time, or in the configuration.
 That way it would be explicit that this is meant as a way to explicitly
 turn off ancient zombies, not actively used Tors?

 Maybe there should be a warning phase before final cutoff for each
 version?

 One issue to consider here is that this is a matter for long-term
 planning.  Even if we put this into 0.2.7 today, we will still need a plan
 to get all existing clients off the network someday.

 Wrt modified or independent clients: that's a separate question.  In my
 experience, botnet jerks don't feel like doing much more work then needed,
 and don't feel like kludging their Tor binaries very hard.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/15935#comment:3>
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