[tor-bugs] #27921 [Core Tor/Tor]: apparent DOS / impariment-of-service against FallbackDirs using DIR requests, please evaluate for possible mitigation

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#27921: apparent DOS / impariment-of-service against FallbackDirs using DIR
requests, please evaluate for possible mitigation
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 Reporter:  starlight           |          Owner:  (none)
     Type:  enhancement         |         Status:  new
 Priority:  Medium              |      Component:  Core Tor/Tor
  Version:  Tor: 0.3.4.1-alpha  |       Severity:  Normal
 Keywords:                      |  Actual Points:
Parent ID:                      |         Points:
 Reviewer:                      |        Sponsor:
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 Early this year I noticed excessive DIR requests against my relay and also
 in the Relay Search usage graphs of other fallback directory nodes.  Wrote
 an iptables rule and put an end to it.

 The attacker enhanced their botware to request via OR port and the problem
 is back.  In the previous 24-hour stats window DIR requests increased
 output load on the relay by 17%.  In the current cycle the increase is
 12%.

 Opening this ticket to put the problem on the radar.  When time permits
 (never enough time, I know) and/or the attack escalates please investigate
 an enhancement to DOS mitigation to address this issue.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/27921>
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