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Re: Is three hops enough? (was Re: Tor client over a SOCKS proxy, and Tor client running through another Tor Circuit)
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Ringo Kamens wrote:
> Well, that 1/3 statement is if every circuit were to be
> compromised. I have noticed that there are some servers on the DoD
> Information Network (Kind of like how NRC runs freenet nodes). I
> also noticed some servers at nato c3. (They were blocked by
> peerguardian while I was trying to connect). I do believe 5 is a
> good amount, and I'm interested on how to change it.
> On 4/28/06, *glymr* <glymr_darkmoon@xxxxxxx
> <mailto:glymr_darkmoon@xxxxxxx>> wrote:
> Anthony DiPierro wrote:
>> On 4/27/06, Ringo Kamens < 2600denver@xxxxxxxxx
> <mailto:2600denver@xxxxxxxxx>> wrote:
>>> I don't really see anything wrong with it if you really want
> to do it. It
>>> doesn't really increase anonymity, but it sounds good to me.
> I'm assuming
>>> that tor2 sees the ip address of the tor 1 exit node.
>> The way I picture it it would basically be equivalent to
> adding extra
>> hops. I remember reading this is possible to hack into the
>> tor software, but I believe it requires a recompile and not just
>> a config file tweak.
>> Anyway, it is my understanding that the current default
>> uses three hops. Now am I correct that that includes the exit
>> Does it also include the entry node which is generally on the
>> same computer?
> this is incorrect, the entry node, middleman node and exit node are
> separate from the client. if one is running a tor server the entry
> node is indeed the same node but remember a tor server is
> shuffling every other packet from other circuits mixed in with
> yours, and thus it seems logical that it would improve anonymity
>> If so, it seems that in the current default implementation
> only one
>> compromised node, the middle node (working with the
> destination site),
>> is needed to significantly impact your anonymity. The IP
> address of
>> the exit node is generally recorded in web logs along with the
>> and date. So if the middle node records the incoming and
>> outgoing node IP addresses, that can then be matched up with the
> logs. If
>> someone is using three hops the way I described it above, then
>> incoming IP address would be the address of the tor user, right?
>> Sure, you'd have a little bit of plausible deniability, as
> there's no
>> proof your system was set up this way, but that's it.
>> Now hopefully I'm just wrong about what constitutes three hops
>> (or that the default setting is three hops). Or maybe I'm
>> missing something as to why this type of attack isn't possible.
>> One thing seems almost certain, adding hops does increase the
>> against a compromised node attack.
> a compromised node attack, on average, has to compromise 1/3 of the
> entire tor network to get somewhere approaching good odds of being
> able to identify the endpoints of circuits. possibly 2/3, but i'd
> say 1/3 of nodes being compromised would give usable violation of
> the system... as you may know, there is something like 300-400
> servers in the tor network now, to compromise it they'd have to put
> up like 150-200 new compromised nodes, or hack and compromise
> 100-150, either task is not trivial at all.
i think that it would be useful if someone would make a peerguardian
list of possibly suspect nodes so people could run them with tor to
help defend against this problem
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