[tor-bugs] #5028 [Ooni]: Tor bridge scanning

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#5028: Tor bridge scanning
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 Reporter:  hellais  |          Owner:  runa                     
     Type:  project  |         Status:  assigned                 
 Priority:  normal   |      Milestone:  Sponsor F: March 15, 2012
Component:  Ooni     |        Version:                           
 Keywords:           |         Parent:                           
   Points:           |   Actualpoints:                           
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Comment(by karsten):

 Replying to [comment:45 karsten]:
 > A manual analysis of the bridge usage statistics reported by the 14
 reachable bridges confirms that these bridges are actually reachable from
 .cn: 1 bridge reported 24 connections from .cn, 5 bridges reported 16
 connections, 6 bridges reported 8 connections, and 2 bridges didn't report
 country statistics.  The bridge usage statistics reported by the 80
 presumably blocked bridges have not been analyzed.

 I looked closer at the scan results and compared bridge statistics of
 reachable and unreachable bridges.  Here's a graph of the number of
 bridges reporting a given number of Tor connections within a 24-hour
 interval.  Bridges in the first bin reported 1 to 8 connections, bridges
 in the second bin 9 to 16 connections, and so on.  Bridges in the red
 parts were found unreachable by our scans, those in the green parts were
 found reachable.

 [[Image(ticket:5028:bridge-scan-eval-2012-03-15.png)]]

 It seems that our scan results aren't entirely random.  The vast majority
 of bridges we couldn't reach reported 1 to 8 connections, whereas a fair
 fraction of reachable bridges reported 9 to 24 or even 57 to 64
 connections.  On average, unreachable bridges reported 5 connections,
 reachable bridges reported 17 connections.

 I also attached the
 [https://trac.torproject.org/projects/tor/attachment/ticket/5028
 /sanitized-logs-2012-03-15.csv scan results] containing fingerprint hashes
 matching the ones in [https://metrics.torproject.org/data.html#bridgedesc
 sanitized bridge descriptors] for future analysis.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5028#comment:48>
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