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

[Tor Bug Tracker & Wiki]

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

Comment(by karsten):

 I ran a scan on my host in .de this morning.  I scanned 313 bridges in the
 HTTPS pool that were contained in the bridge pool assignments file from
 March 13, 06:30:18 UTC and in the network status published at 06:37:04
 UTC.  The scan ran from 07:19:30 to 07:23:44 UTC and resulted in 300
 bridges being reachable and 13 bridges being unreachable:

  - 299 bridges that were found as reachable were contained in both network
 statuses published at 06:37:04 and 07:37:04 UTC.  Scan results are
 correct.
  - 1 bridge that was found as reachable was only contained in the network
 status published at 06:37:04 UTC and not in the one published at 07:37:04
 UTC.  That means that Tonga could not reach this bridge, but the scanner
 could.  This is an actual false positive.
  - 9 bridges that were found as unreachable had the Running flag in the
 assignments file from 06:30:18 UTC and in the network status from 06:37:04
 UTC, but lost it in the network status published at 07:37:04 UTC.  These
 negative scan results are correct.
  - 2 bridges that were found as unreachable were contained in the
 assignments file from 06:30:18 UTC but did not have the Running flag in
 the network statuses published at 06:37:04 and 07:37:04 UTC.  These
 bridges went offline between 6:30 and 6:37 and should not have been
 scanned at all.  Can't blame the scanner for that.
  - 2 bridges that were found as unreachable were contained in the
 assignments file and all both network statuses, and they were reachable in
 a subsequent scan at 09:00:55 UTC.  These 2 are actual false negatives.

 So, 1 false positive and 2 false negatives.  Should be fine.

 The next step will be to run a similar scan from .cn.

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/5028#comment:35>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online