Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-15 Thread nusenu 


Moritz Bartl:
> Which is sadly not the case. Our MyFamily statements are badly out of
> sync. Will fix this next week.

Looking forward to a safer tor network!


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Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-10 Thread Gareth Llewellyn 
On Sat, Jun 10, 2017 at 10:39 AM, Moritz Bartl 
wrote:

>
> We had to temporarily disable some of our exits due to ongoing
> negotiations with the provider.
>
>
Will your provider allow BGP announcements of other IP space?

Depending on how many exits we're talking about I (BrassHornCommunications
/ AS28715) will happily 'loan' you a /24 and a /48-/36 to route from which
will remove the abuse complaints from your provider.

(FWIW I'd rather not give up a /24 if you're happy using your providers v4
for general Tor routing and AS28715's IPv6 for exiting that'd be ideal).

Alternatively I can sponsor your RIPE v6 PI application (subject to the new
rules about having a 'contractual relationship yadda yadda) if you'd like
to do that.
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Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-10 Thread Toralf Förster 
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On 06/08/2017 02:00 PM, Paul Syverson wrote:
> It shouldn't be possible to use the relay in both positions
> simultaneously.
As long as "MyFamily" is correctly set, yes IMO.

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Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-10 Thread Moritz Bartl 
On 08.06.2017 14:00, Paul Syverson wrote:
> circuit. And if all torservers.net relays are properly indicated to be
> from the same family, they will never be selected for both ends of a
> circuit.

Which is sadly not the case. Our MyFamily statements are badly out of
sync. Will fix this next week.

We had to temporarily disable some of our exits due to ongoing
negotiations with the provider.

Thank you nusenu for watching out!

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https://www.torservers.net/
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Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-08 Thread nusenu 
Hi Paul,

Paul Syverson:
> It shouldn't be possible
> to use the relay in both positions simultaneously.  And even if it
> could serve as both guard and exit simultaneously, the route-selection
> algorithm would preclude it being used as both ends for any
> circuit. And if all torservers.net relays are properly indicated to be
> from the same family, they will never be selected for both ends of a
> circuit.

I'm well aware of how MyFamily works :)

To quote the page I linked (OrNetStats):

> Operators are only listed if they actually have a chance to do end-to-end 
> correlation attacks, that is:
> their guard and exit probability is > 0%
> they did not properly configure MyFamily
> they run in more than a single /16 network block

For more context see:
https://medium.com/@nusenu/some-tor-relays-you-might-want-to-avoid-5901597ad821


> Potentially, a client opening multiple circuits through multiple
> guards (so not using the current standard default of using a single
> guard) could have some guards and some exits of concurrent circuits
> run by torservers.net if they satisfy the /16 separation.
> But that is generally not what is meant by 'end-to-end correlation'.

By end-to-end correlation I mean "a tor client has a chance to use
torservers.net relays in their entry (guard) and exit position in a
single circuit.


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Re: [tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-08 Thread Paul Syverson 
Hi Nusenu,


On Thu, Jun 08, 2017 at 09:58:00AM +, nusenu wrote:
> Dear Torservers,
> 
> are  you aware that you have recently become a relay operator with
> end-to-end correlation (deanonymization) capabilities? (in fact you are
> the biggest known such operator)
> This is especially bad for tor clients because you are also one of the
> biggest tor exit operators.
> 
> Some of your relays which used to be exits recently became guard-ony relays.
> https://nusenu.github.io/OrNetStats/endtoend-correlation-groups#httpswwwtorserversnetdonatehtml-support-a

Apologies if this is focusing on a minor point of your message or
illuminates nothing but my general tiredness/distractedness, but I
don't see how switching a relay from being an exit to being guard-only
increases correlation risk from that relay. It shouldn't be possible
to use the relay in both positions simultaneously.  And even if it
could serve as both guard and exit simultaneously, the route-selection
algorithm would preclude it being used as both ends for any
circuit. And if all torservers.net relays are properly indicated to be
from the same family, they will never be selected for both ends of a
circuit.

Potentially, a client opening multiple circuits through multiple
guards (so not using the current standard default of using a single
guard) could have some guards and some exits of concurrent circuits
run by torservers.net if they satisfy the /16 separation.
But that is generally not what is meant by 'end-to-end correlation'.

aloha,
Paul
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[tor-relays] torservers.net: some exits became guards? (deanonymization risk)

2017-06-08 Thread nusenu 
Dear Torservers,

are  you aware that you have recently become a relay operator with
end-to-end correlation (deanonymization) capabilities? (in fact you are
the biggest known such operator)
This is especially bad for tor clients because you are also one of the
biggest tor exit operators.

Some of your relays which used to be exits recently became guard-ony relays.
https://nusenu.github.io/OrNetStats/endtoend-correlation-groups#httpswwwtorserversnetdonatehtml-support-a


Is there anything I can help you with to fix this and reduce the risk
for tor clients?

thanks,
nusenu






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