[tor-relays] Nagios/Icinga plugin check_tor_bandwidth for gathering bandwidth data

[Tim Wilson-Brown - teor]

> On 26 Nov 2015, at 05:36, Josef Stautner <hello at veloc1ty.de> wrote:
> 
> Hello @all,
> 
> (I'm not sure if you guys are interested in a topic like this)
> I wrote a perl script to gather bandwidth data from my Tor exit relay.
> The script connects to the Tor control socket, fetches the running
> config to extract the bandwidth limits and the reject rule count.
> Afterwards the last 60 bw-cache entries are fetched and average values
> are built for bandwidth in and out.
> All this performance data is then forwarded to Nagios/Icinga where you
> can do anything with that values.
> 
> Every 30 minutes a cronjob renders the graph showing the datapoints of
> the last 6 houres and uploads the resulting image to my website. You can
> find the image here (Hint: The values for in and out are stacked):
> https://blog.veloc1ty.de/bandwidth-large.png
> 
> The source of the script can be found here on GitHub:
> https://github.com/vlcty/check_tor_bandwidth
> It's released under the GPLv3
> 
> Maybe somebody will find it usefull :-)

Hi Josef,

Thanks for creating this tool - it looks like a great way for operators to keep an eye on their relay.

But I wonder about the privacy implications of making a relay's high-resolution bandwidth figures public.
For example, attacker can correlate a traffic-based attack on a hidden service, with a traffic peak on its Guards.
(I am not sure if any similar attack applies to Exits, or any other role Exits may have.)
We previously moved to a bandwidth statistics interval of 6 hours for this reason.
(That's why the 3 days and 1 month bandwidth graphs are empty on Globe.)

You lose a certain amount of precision moving to a graph, rather than reporting exact figures in a data file.
But I'm not sure if that's enough to avoid the attack I described above.

Tim

Tim Wilson-Brown (teor)

teor2345 at gmail dot com
PGP 968F094B

teor at blah dot im
OTR CAD08081 9755866D 89E2A06F E3558B7F B5A9D14F

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