It appears that having Guard-Exit node in Tor increase the probability of deanonymizing the client compare to Guard and exit node separately. To put it in a nutshell if a node at times could become your Guard node and at other times could become your exit node even in a same session (look at this question for reference What is the risk of guard relay and exit relay being one and the same?), it might be able to integrate these information and thus facilitate client deanonymization. For further reference also please look at this question Why adding Guard-Exit (EE) node in Tor yeild more catch probability than adding guard and exit node separately?

Under these circumstances, why would Tor allow Guard-Exit node?

1 Answer 1


i'm programming in python an application related to Tor with stem library.

when i create new paths sometimes the guard node (entry) belongs to the same family (group of servers) as the exit node. This is close to your case the main problem that carries in both cases the connections can be analyzed based on time responses and patterns and being 'uncovered'. Exist many studies about it, this is the last one i found and the newest, link .

actually this can be an answer to your question : What is the risk of guard relay and exit relay being one and the same?

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    Dear Psa, as I understand from your answer, you confirm that this is indeed happening and also will facilitate deannoymization of clients. But why do you think Tor people allow this to happen for such a long time?
    – Roya
    Dec 3, 2014 at 19:56
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    I was taught that sometimes software's characteristics could become/cause a weakness. how can you resolve it in Tor?(just guessing) i mean, i knew that some relays are family because at first sight was obvious because of their ip's i also check it here torstatus.blutmagie.de.
    – Psa
    Dec 3, 2014 at 23:43
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    (Continue)But if you own some relays it's not necessary to coordinate them as a family even you can omit this information (it says "No Info Given" in the link's page). you could put some independent relays(guard and exit) and not coordinate them through Tor, by this way you wouldn't know to whom they belong to, but who knows maybe Tor project team will find a way to resolve it somehow, anyway it not easy to deanonymize a client, it takes time.Have in mind a guard node changes every 2 weeks and your path every 10 min!
    – Psa
    Dec 3, 2014 at 23:43

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