[tor-relays] [OT] ExcludeNodes no longer working

[Scott Bennett]

     I know this really belongs on tor-talk, but I haven't been subscribed
to it for a long time now.  Sorry if posting this here bothers anyone.
     Back in early July, I upgraded from 0.2.3.13-alpha to 0.2.3.18-rc.
I immediately ran into problems with a python script that honors the
http_proxy environment variable, which I normally have set to the localhost
port for privoxy, which, in turn, connects to tor's SOCKS port.  I couldn't
really see what was going wrong, but using arm to ask for a new identity
seemed to help sometimes to get a circuit that worked.  Sending tor a
SIGHUP instead also seemed to work about as often.
     A bit over a week ago, I switched to 0.2.3.20-rc, and the problem
still occurs.  However, 0.2.3.20-rc now also emits a new message from time
to time, the most recent occurrence of which is

Sep 06 06:02:45.934 [notice] Low circuit success rate 7/21 for guard TORy0=753E0B5922E34BF98F0D21CC08EA7D1ADEEE2F6B.

Wondering whether such circuit-building failures might be related to the
other problem, I began a little experiment:  each time I saw a "Low circuit
success rate" message, I added the key fingerprint of the node in question
to my ExcludeNodes list in torrc and sent tor a SIGHUP.
     The problem is still occurring, though, and when I look at the
circuits involved, they all seem to have at least one of the excluded
nodes in them, usually in the entry position.  So my question is, what
changed between 0.2.3.13-alpha and 0.2.3.18-rc (or possibly 0.2.3.20-rc)
in the handling of nodes listed in the ExcludeNodes line in torrc?  And
is there anything I can do to get the ExcludeNodes list to work again
the way it used to work?
     Thanks in advance for any relevant information.


                                  Scott Bennett, Comm. ASMELG, CFIAG
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* Internet:       bennett at cs.niu.edu                              *
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