Opened 4 years ago

Closed 3 years ago

#13208 closed task (fixed)

What's the average number of hsdir fetches before we get the hsdesc?

Reported by: arma Owned by:
Priority: Medium Milestone: Tor: 0.2.8.x-final
Component: Core Tor/Tor Version: Tor: 0.2.7
Severity: Normal Keywords: tor-hs
Cc: Actual Points:
Parent ID: #13209 Points: small
Reviewer: Sponsor: SponsorR

Description

Hidden services publish their hsdesc to six hsdir relays, once an hour.

Then relays come and go, changing the set of six that clients will compute when deciding which relay to fetch from.

Also, both hidden services and clients only fetch a new consensus every 2-4 hours, so they will be perenially a few hours behind.

This could pretty easily result in a situation where (due to different knowledge on the hidden service's part) the hidden service doesn't publish to all six that it's "supposed" to, and (due to different knowledge on the client's part) the client doesn't pick from the same six that the hidden service published to, and (due to churn in the relays) the six that the hidden service published to might not remain the right six from a global perspective.

Realistically, do these skews matter?

We could imagine doing an experiment where we follow the client algorithm and find out the average number of fetches we do before we get an answer (or give up).

Child Tickets

Change History (10)

comment:1 Changed 4 years ago by arma

Parent ID: #13209

comment:2 Changed 4 years ago by nickm

Milestone: Tor: 0.2.???Tor: 0.2.7.x-final

These may be worth looking at for 0.2.7.

comment:3 Changed 4 years ago by nickm

Status: newassigned

comment:4 Changed 4 years ago by nickm

Keywords: 027-triaged-1-in added

Marking more tickets as triaged-in for 0.2.7

comment:5 Changed 4 years ago by isabela

Points: small
Priority: normalmajor
Version: Tor: 0.2.7

comment:6 Changed 3 years ago by nickm

Milestone: Tor: 0.2.7.x-finalTor: 0.2.8.x-final

comment:7 Changed 3 years ago by nickm

Keywords: SponsorR removed
Sponsor: SponsorR

Bulk-replace SponsorR keyword with SponsorR sponsor field in Tor component.

comment:8 Changed 3 years ago by dgoulet

Keywords: 027-triaged-1-in removed

comment:9 Changed 3 years ago by nickm

Priority: HighMedium

comment:10 Changed 3 years ago by dgoulet

Resolution: fixed
Severity: Normal
Status: assignedclosed

FYI, we do this experiment with #13209 and using the _latest_ consensus, we get ~3.06% chances of one single fail fetched done for 6 different long live HS such as Facebook and DDG.

http://ygzf7uqcusp4ayjs.onion/tor-health/tor-health/hs_health_fail_prob.html

I'm going to close this one because we've been tracking this since October. However, we could improve our experiment to use a regular tor client instead of latest consensus or use different consensuses spread over 12 hours for instance. If we want to do that, let's open a new ticket for such improvement. For now, we have the basics.

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