Firefox ignores trr = 3 when resolving detectportal.firefox.com and incoming.telemetry.mozilla.org
Categories
(Core :: Networking: DNS, defect)
Tracking
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Tracking | Status | |
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firefox72 | --- | affected |
People
(Reporter: etrapani, Unassigned)
References
Details
(Keywords: nightly-community)
If network.trr.mode = 3 (only use TRR) Firefox still resolves the following address with the native resolver.
detectportal.firefox.com
Reporter | ||
Comment 1•5 years ago
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While quitting, it also resolves incoming.telemetry.mozilla.org with the native resolver.
Updated•5 years ago
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Comment 2•5 years ago
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IIRC it's on purpose. Is that right, Valentin?
Comment 3•5 years ago
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Yes, this is on purpose. Captive portal detection is useless if you don't use the native resolver.
The when quitting
bit is not expected, but we have a different bug for that.
Reporter | ||
Comment 4•5 years ago
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(In reply to Valentin Gosu [:valentin] (he/him) from comment #3)
Yes, this is on purpose. Captive portal detection is useless if you don't use the native resolver.
I get it, but the idea of trr = 3 is not to use the local resolver ever. Maybe there should be no detection with that setting then.
The
when quitting
bit is not expected, but we have a different bug for that.
I cannot find it, could you please provide the number so that I can add me to the CC list?
Comment 5•5 years ago
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(In reply to Eduardo Trápani from comment #4)
The
when quitting
bit is not expected, but we have a different bug for that.I cannot find it, could you please provide the number so that I can add me to the CC list?
Ooops, missed this ni.
I was wrong that we had a different bug for that. That is actually expected behaviour, since it happens in a different process:
https://searchfox.org/mozilla-central/rev/803a42f24c8714631ed81cb824ea1c1a803cb7b8/toolkit/components/telemetry/fog/src/lib.rs#162
Reporter | ||
Comment 6•5 years ago
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Somebody setting network.trr.mode =3 is clearly asking Firefox to be DNS-silent (standard resolution). The fact that instead the user gets a beacon at the beginning and end of the session is rather unexpected.
From the wiki https://wiki.mozilla.org/Trusted_Recursive_Resolver, the native resolver is NEVER used.
3 - Only. Only use TRR. Never use the native (This mode also requires the bootstrapAddress pref to be set)
Comment 7•5 years ago
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(In reply to Eduardo Trápani from comment #6)
Somebody setting network.trr.mode =3 is clearly asking Firefox to be DNS-silent (standard resolution). The fact that instead the user gets a beacon at the beginning and end of the session is rather unexpected.
There are some important notes here:
- We exclude the captive portal domain because by definition the captive portal works with local DNS. Doing the checks using TRR doesn't make much sense.
- There are other ways we intentionally bypass mode3: if you've got OS level parental controls on, for the domains in
network.trr.excluded-domains
for any subdomains of the DNS suffix list (such as .lan, .local, etc)
In any case, I filed bug 1610365 to reconsider the telemetry question.
Comment 8•5 years ago
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You can network.captive-portal-service.enabled to false to get rid of that in about:networking#dns...
Description
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