Question regarding Vanguards selection process

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1

Hey all!
According to Tor documentation, vanguards are chosen from relays that have the Fast and Stable flags. I understand that part.

My question is: does that mean an exit‑only relay with both Fast and Stable flags can technically be selected as an L2 vanguard?

If so, is there a way to calculate the probability of this happening? I’ve seen middle_probability in the Onionoo API, but I don’t know if that is meaningful here. Are vanguards even considered “middle position” relays for that purpose, “the HS REND circuits”? and if that’s true then looking at the middle_probability for evey exit-only relay it’s 0! so that means Vanguards(L2 & L3) cannot be exit-only relays?

I hope someone can answer my question :folded_hands:

and I am sorry if my post has an issue with it, this is my first post here!

Thank you so much!

2

I would say yes, every middle relay you describe can be L2.

This describes how vanguards are used. It mentions always middle relays. And exits are middle relays.

Cheers

3

Thank you so much for your answer!

and I hope you could also answer this one also

Why when I tried to trigger Vanguards so many times to change by restarting tor and connecting to my HS, every vanguard(L2) was never an Exit-only relay? , keep in mind I did it over 1000 times! either Guard or Middle-Only or none of those flags but never exit only? is it because even though it can technically be an exit-only but the probability of that is very low? and also why the middle_probability for exit-only relays is always 0 in Onionoo API?

Thank you so much in advance!

4

Oh that is a lot :grinning_face_with_smiling_eyes:

I did a test and manually forced L2 with an exit relay (fast, stabile, not hsdir, on my choice) via HSLayer2Nodes in torrc and it worked fine. So technically it seems to work.

Of course I value your observation.

Cheers

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