[tor-bugs] #10418 [Tor Launcher]: Make a "Use Default Bridges" Radio button in the Tor Launcher Bridge UI

Tor Bug Tracker & Wiki blackhole at torproject.org
Thu Mar 6 16:53:16 UTC 2014

#10418: Make a "Use Default Bridges" Radio button in the Tor Launcher Bridge UI
     Reporter:  mikeperry     |      Owner:  brade
         Type:  enhancement   |     Status:  reopened
     Priority:  major         |  Milestone:
    Component:  Tor Launcher  |    Version:
   Resolution:                |   Keywords:  MikePerry201402R
Actual Points:                |  Parent ID:
       Points:                |

Comment (by brade):

 Replying to [comment:39 mcs]:
 > I wonder if there is a race inside tor between starting the client
 transport plugins and trying to use the bridges?  As we discussed, when
 default bridges are configured, Tor Launcher always starts tor with
 DisableNetwork=1.  Then it does a SETCONF to set UseBridges=1 and to
 configure the bridges (Bridge=<list>).  Then it does a second SETCONF with

 We did a little more investigation and learned that the "can't find a
 pluggable transport proxy
 supporting 'obfs3'" warnings are emitted by tor even if tor is started
 with networking enabled and if no SETCONF commands are issued by Tor

 Interestingly, if we remove cached-descriptors and cached-descriptors.new
 before starting TBB, those warnings are not emitted by tor.

 Here are some steps to reproduce the problem just by running tor at the
 command line.

 1) Download and install one of GK's TBB builds from
 https://people.torproject.org/~gk/builds/3.6-beta-1/ (we tested on Mac

 2) edit Data/Tor/torrc and place these lines in it:
 Bridge obfs3 A09D536DD1752D542E1FBB3C9CE4449D51298239
 Bridge obfs3
 Bridge obfs3
 Bridge obfs3 AF9F66B7B04F8FF6F32D455F05135250A16543C9
 Bridge obfs3 BA61757846841D64A83EA2514C766CB92F1FB41F
 Bridge obfs3 AF9F66B7B04F8FF6F32D455F05135250A16543C9
 UseBridges 1

 3) Run tor like this:
 cd Tor
 ./tor --defaults-torrc ../Data/Tor/torrc-defaults -f ../Data/Tor/torrc \
       --DataDirectory ../Data/Tor GeoIPFile ../Data/Tor/geoip

 4) Run tor a second time and you will see some "can't find a pluggable
 transport proxy
 supporting 'obfs3'" warnings.  Also, netstat will probably show outbound
 TCP connections to some of the bridges for which warnings were emitted...
 which does not make a lot of sense to me.  The warnings seem spurious.

 5) rm Data/Tor/cached-descriptors and run tor a third time.  The warnings
 will not be emitted.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/10418#comment:40>
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