[tor-relays] Guard flag flapping

Green Dream greendream848 at gmail.com
Sun Aug 9 19:52:21 UTC 2015

> A simple test you could run on your server is fetching directory info
> from nodes that have directory functionality enabled.

Thanks for the idea. blutmagie offers a CSV list of its current result set,
so this ended up being quite easy to automate.

I fetched a copy of the CSV to the server:

  wget https://torstatus.blutmagie.de/query_export.php/Tor_query_EXPORT.csv

Then I picked out the columns I cared about, included only Exits with a
Dirport, then sorted by the bandwidth column, and grabbed the fastest 50:

   awk -F \, '{if ($10 == "1" && $8 != "None") print $3, $5, $8}'
Tor_query_EXPORT.csv | sort -nr | head -50 > top-50-exits-with-dirport.txt

That file now looks like:

34994 80
33134 443
30736 21
30720 80
26958 80

So we now have the bandwidth, IP, and dirport of the fastest exits. With
this list in hand, I just needed to form a proper URL, wget each one, and
grep out the transfer speed:

   for URL in $(awk '{print "http://" $2 ":" $3 "/tor/server/all"}'
top-50-exits-with-dirport.txt); do printf "$URL " && wget $URL -O /dev/null
2>&1 | grep -o "[0-9.]\+ [KM]*B/s"; done

The output ends up looking like this (only displaying the first 10 for
brevity): 1.17 MB/s 4.54 MB/s 666 KB/s 111 KB/s 330 KB/s 3.65 MB/s 2.20 MB/s 13.4 MB/s 347 KB/s 295 KB/s

I'm not seeing anything immediately, although I need to run it on a larger
set. There's no smoking gun so far though. Some of the speeds are a bit
slow, but nothing low enough to explain the extremely low measured
bandwidth these relays are getting. I think I'll clean this up a bit, put
it into an actual script, and try running it on another server on a
different AS for comparison.
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