[tor-bugs] #28655 [Obfuscation/BridgeDB]: If a bridge supports obfs4, don't give out its other flavors

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#28655: If a bridge supports obfs4, don't give out its other flavors
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 Reporter:  arma                  |          Owner:  phw
     Type:  defect                |         Status:  needs_review
 Priority:  High                  |      Milestone:
Component:  Obfuscation/BridgeDB  |        Version:
 Severity:  Normal                |     Resolution:
 Keywords:  bridgedb              |  Actual Points:
Parent ID:                        |         Points:  2
 Reviewer:                        |        Sponsor:  Sponsor19
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Comment (by phw):

 I wanted to understand how many bridges would be affected by this patch. I
 took an assignments.log file that BridgeDB created on 2019-04-19. Here's
 what the file can tell us:

 ||= Description =||= # =||= % =||= Command =||
 || All bridges || 968|| 100.0|| `wc -l assignments.log` ||
 || Bridges that have a transport protocol || 258|| 26.7|| `grep -c
 transport assignments.log` ||
 || Bridges that have obfs4 || 249|| 25.7|| `grep -c obfs4 assignments.log`
 ||
 || Bridges that have obfs4 or scramblesuit || 251|| 26.0|| `grep -c
 '\(obfs4\|scramblesuit\)' assignments.log` ||
 || Bridges with obfs or scramblesuit and obfs2, obfs3, or fte || 38||
 3.9|| `grep '\(obfs4\|scramblesuit\)' assignments.log | grep -c
 '\(obfs2\|obfs3\|fte\)'` ||

 The numbers show that we have 251 bridges that are active probing-
 resistant. 38 (15%) of these bridges ''also'' run a transport that is not
 active probing resistant---obfs2, obfs3, and/or fte. After fixing this
 ticket, we will stop handing out these transports.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28655#comment:13>
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