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Firefox’s Trusted Recursive Resolver DNS feature is dangerous

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Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#61
DNS over HTTPS is a great idea. There's nothing wrong with the protocol or Mozilla's implementation of it. This article is all about Mozilla's default choice for a DNS provider. I think Cloudflare is actually a reasonable choice though I'm not a big fan of their annoying captchas that I get served whenever I use vpns.

There's nothing sneaky going on here; which the article seems to imply.

Currently there is no UI to configure any of this yet (other than about:config) but you can trivially select any DNS provider that implements this in the same place where you turn this on. The relevant setting is network.trr.uri. Also, you need to opt in to this to turn it on so you'd be reviewing this setting as well. Also you can configure how this is used, how and when it falls back to normal DNS, etc.

You can run your own server if you want; or use the one from your provider if/when they implement this. For obvious reasons, there are not a lot of usable servers yet but it seems Google has implemented this as well. So I assume they plan to roll this out for Chrome at some point.

The premise of this article seems to be that you should trust your provider to do DNS and do it well. I'm sorry to say but for the vast majority of providers I have experience with the opposite is the case. I've had providers redirect dns failures to advertising pages in the past, shitty performance (600 ms or worse), and generally trying to rip me off with bad network infrastructure related outages while charging me a premium for bandwidth clearly not delivered via obviously very congested infrastructure. I have no reason whatsoever to trust them, at all. The less they can learn from my traffic the better.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#62
post #22

The article lacks instructions about disabling it or using some other DOH resolvers. about:config -> search for network.trr -> set network.trr.mode = 5 to completely disable it (I do not recommend this) The curl wiki has a list of DOH servers: https://github.com/curl/curl/wiki/DNS-over-HTTPS It should also point to "the other side of the story", the benefits of DOH over classic DNS resolving, for example https://hack…

Thanks for the hint! We added that to our blog entry - please let us know if it sounds right to you.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#63
post #34
post #7

What about if you have private DNS servers that has sites that cloudflare does not have? For example internal intranets etc? So mozilla will not work at all in that case?

That one actually breaks in the new release :-/

Is there a tracking bug for this on Mozilla's bugzilla?

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#65

I use Cloudflare's resolver, but I actually agree with this. I don't want every device in my local network ignoring my Pi hole or my custom DNS entries, I don't want the device of everyone in my country being subject to surveillance requests from the NSA (and Cloudflare is legally (if you call warrantless wiretaps legal) required to comply), and I don't like the centralization this brings. If I recall correctly, this…

> I don't want the device of everyone in my country being subject to surveillance requests from the NSA (and Cloudflare is legally (if you call warrantless wiretaps legal) required to comply), and I don't like the centralization this brings.

Agreed that this introduces additional centralization. Maybe Mozilla could work to with other third parties in different jurisdictions to see if there's interest to spin up additional DOH servers. That said, if your threat model includes the NSA then this would probably be far from sufficient.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#66

> My local ISP seems more trustworthy to me than a big US-based corporate which acts under the guise of a selfless privacy rights defender. I have never trusted any local ISP. They’re commonly expressly allowed by law to share roughly whatever they like about you†, and they are known to do so . Cloudflare has at least promised not to be evil, and is to be audited annually concerning it. If they desire to be evil I ha…

> Cloudflare has at least promised not to be evil

Remember when Google did so, too? Then they bid on military contracts and bought a military contractor.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#67
post #52

> My local ISP seems more trustworthy to me than a big US-based corporate which acts under the guise of a selfless privacy rights defender. I have never trusted any local ISP. They’re commonly expressly allowed by law to share roughly whatever they like about you†, and they are known to do so . Cloudflare has at least promised not to be evil, and is to be audited annually concerning it. If they desire to be evil I ha…

> They’re commonly expressly allowed by law to share roughly whatever they like about you†, and they are known to do so. Why would this not apply to Cloudflare as well?

Because you may live in a country where the government is much more hostile than cloudflare.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#68
post #59

That s just a feature. You can choose not to use it. Why so much noise?

As I understand it that's even the default choice, and CloudFlare is just the provider they're currently testing this with for those who do choose and do not configure their own provider.

Re: Firefox’s Trusted Recursive Resolver DNS feature is dangerous

#70

DNS over HTTPS is a great idea. There's nothing wrong with the protocol or Mozilla's implementation of it. This article is all about Mozilla's default choice for a DNS provider. I think Cloudflare is actually a reasonable choice though I'm not a big fan of their annoying captchas that I get served whenever I use vpns. There's nothing sneaky going on here; which the article seems to imply. Currently there is no UI to…

The article doesn't suggest there's something sneaky going on. The article is suggesting that Mozilla are choosing to share your DNS queries with a third party service by default, which is exactly what they're doing. It's not about them choosing Cloudflare in particular, it's about them choosing any particular service by default. And the article's argument that, if you have to choose somebody to share this data with, it might as well be the people you already share it with, seems pretty valid to me.

edit: I have to point out that the article has backed away from the claim that this will be enabled by default in September. Looking at the Mozilla blog, they mention wanting to enable this by default but have no actual plan to do so (and more crucially doesn't discuss at all what sort of form it would have to be in for them to enable it by default, it may look nothing like the cloudflare-default we're discussing here).

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