[tor-bugs] #19071 [Core Tor/Tor]: Check existing fallback fingerprints, IPs, and ports before 0.2.8-rc

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#19071: Check existing fallback fingerprints, IPs, and ports before 0.2.8-rc
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  teor
     Type:  enhancement                          |         Status:
 Priority:  Medium                               |  needs_review
Component:  Core Tor/Tor                         |      Milestone:  Tor:
 Severity:  Normal                               |  0.2.8.x-final
 Keywords:  must-fix-before-028-stable,          |        Version:  Tor:
  TorCoreTeam201606                              |  0.2.8.2-alpha
Parent ID:                                       |     Resolution:
 Reviewer:                                       |  Actual Points:  0.5
                                                 |         Points:  0.5
                                                 |        Sponsor:
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Changes (by teor):

 * status:  new => needs_review
 * keywords:  must-fix-before-028-rc, TorCoreTeam201606 => must-fix-
     before-028-stable, TorCoreTeam201606
 * actualpoints:   => 0.5


Comment:

 Please see my branch bug19071-v2 on https://github.com/teor2345/tor.git
 based on maint-0.2.8.

 7e9532b, b15cecd, 69635e4:
 These commits remove 9 fallbacks from the hard-coded list, because:
 * their details have changed (2),
 * they are slow to serve consensuses (2),
 * they are down permanently (3),
 * they have poor uptime (1), or
 * they lost the Guard flag (1).

 7e9532b, 69635e4:
 These commits blacklist 7 fallbacks for future releases, because:
 * their details have changed (2),
 * they are slow to serve consensuses (2), or
 * they are down permanently (3).

 Some of the whitelist entries are 6 months old now, so losing 10% in 6
 months seems like an acceptable rate. (A linear projection would see a
 loss of 40% of the fallbacks over the 2-year life of a release, at which
 point 0.4^3 = 6.4% of clients would contact an authority after taking 10
 seconds to try 3 bad fallbacks.) As we blacklist unstable fallbacks, we
 should see better fallback stability in future releases.

 0a79e92:
 This commit modifies the whitelist and blacklist based on from operator
 emails. We'll use these updated lists for future fallback selection.

 4090612:
 This commit fixes updateFallbackDirs.py to avoid errors when there are no
 fallbacks.

 6ce5366:
 This commit adds some comments explaining how to test the list of
 fallbacks before a release.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/19071#comment:5>
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