[tor-bugs] #30368 [Obfuscation/Snowflake]: Run some tests to check reachability of snowflake proxies

Tor Bug Tracker & Wiki blackhole at torproject.org
Fri May 3 17:52:15 UTC 2019


#30368: Run some tests to check reachability of snowflake proxies
-----------------------------------+--------------------------
 Reporter:  cohosh                 |          Owner:  cohosh
     Type:  task                   |         Status:  assigned
 Priority:  Medium                 |      Milestone:
Component:  Obfuscation/Snowflake  |        Version:
 Severity:  Normal                 |     Resolution:
 Keywords:                         |  Actual Points:
Parent ID:                         |         Points:
 Reviewer:                         |        Sponsor:
-----------------------------------+--------------------------

Comment (by cohosh):

 Here's a branch that does probing of snowflake proxies:
 https://github.com/cohosh/bridgetest/tree/snowflake

 Some notes:
 - we make 10 tries to connect through snowflake per probe period. This is
 to ensure we get a reasonable selection of the available proxies. There's
 no guarantee we'll get all of them but this seems like a good number of
 tries for now
 - I cut the Tor connection timeout down to 90 seconds from 180. This is
 because once one proxy hits the 30 second timeout (as described in
 #25429), it will attempt to find another snowflake. However, we only want
 to measure the bootstrap progress for one snowflake at a time. On the
 other hand, this means that in cases where the proxy is reachable, we
 sometimes only see a bootstrap up to 25% or 50% because we didn't give it
 enough time to complete.
 - Snowflake doesn't log the IP address of the snowflake proxies it
 connects to (since #21304) so we have to do a tcpdump and then analysis to
 see which proxy we actually got.

 I'll post some graphs here once we have more data.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/30368#comment:3>
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