[tor-bugs] #29999 [Core Tor/Tor]: Objective 1, Activity 2: Denial of service defences

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#29999: Objective 1, Activity 2: Denial of service defences
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     Reporter:  pili          |      Owner:  (none)
         Type:  project       |     Status:  new
     Priority:  Medium        |  Milestone:
    Component:  Core Tor/Tor  |    Version:
     Severity:  Normal        |   Keywords:
Actual Points:                |  Parent ID:
       Points:                |   Reviewer:
      Sponsor:  Sponsor27     |
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 This is the parent ticket to hold any tickets under this activity,
 including:
 - Reducing the amount of circuits that they build over time on the Tor
 network
 - Providing more ways for onion service administrators to control the
 influx of incoming users in heavy traffic scenarios.
 - Improving our defense mechanisms by:
   - Decreasing onion service load on the Tor network, by slowing down Tor
 circuit creation on startup.
   - Optimizing relevant onion service functions that are called multiple
 times therefore taking a lot of the CPU.
   - Making it harder for adversaries to force services to rotate their
 introduction points.
 - Writing a Tor software change proposal for a “rendezvous approver” API
 that can be useful for:
   1.  Rate limiting; allow at most N unauthenticated clients over a set
 time period
   2.  Extra-conservative logic like "stop accepting connections during
 potential guard discovery"
   3.  Limiting capacity to control server load; only allow N simultaneous
 clients.
   4.  Protocol-tuned rules for things like Ricochet
   5.  More advanced pre-rendezvous authorization
   6.  Load-balancing across multiple servers running Tor onion services
 - Closing client circuit once the INTRO1/ACK dance has been completed,
 decreasing load on the Tor network.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/29999>
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