this post was submitted on 18 Apr 2024
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Privacy
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Dns over https is immune to that firewall method, right?
Yes but I think OP is referring to plain DNS requests to a preferred server.
You can hijack port 53 and redirect them to your preferred server. Also acts as a method of hardening DNS for devices and apps that do not support encrypted DNS.
Forgot to mention the port but that's it. Notorious devices like smart TVs and consoles like to use the hard coded DNS method
Right, and I am pointing out that non-cooperative devices still won't be blocked by pihole if they so desire.
Only if they do encrypted DNS, and you can still block them, you just can't force them to use the DNS you want. Embedded devices tend to avoid encryption to cut down on hardware requirements, they typically even pull their updates over unencrypted connections. IoT is a crazy world. 😃
And may I point out that if you have embedded devices freely connecting to the Internet you have a lot bigger problems than the fact they use encrypted DNS. Hell you should be so lucky for them to use encrypted DNS, at least it would be secure.
What would be an example of an embedded device?
Media players, TVs, IP cameras, lightbulbs... anything with wifi capability really.
Is there a safe way to use these devices? I’m moderately tech savvy at best, and I do worry a lot about my tv. I also use some smart plugs to manage equipment on my aquarium, but that’s it. I’ve considered the implications of these devices, but didn’t know if there was anything I could do about it.
I was making a quick check, and yes, the DoH situation is a bit more dicey. From how I see it, the best way to make this work is to, at the firewall level, either block as much as possible any requests that look like DoH (and hope whatever was using that falls back to regular DNS calls) or setup a local DoH server to resolve those queries (although I am not sure if it is possible to fully redirect those). In that sense, pihole can't really do much against DoH on its own
EDIT: decided to look a bit further on the router level, and for pfsense at least this is one way to do this recipe for DNS block and redirect
Right, so flowing that link there are three ways for DNS:
Classic on port 53,
Dns over TLS on port 853
Dns over https.
The first two can be blocked, because they have specific ports exclusively assigned to them. DoH can't be blocked reliably, because it is encrypted and on a common port. Though blocking 443 on common DNS resolvers can force some clients to fall back to one of the variants that can be blocked/redirected
Who do you think developed DoH? Google has it's paws on everything. It may be private, but as soon as I see Google, I'm out of there.
With most firewalls, there is an option to download ip lists for blocking. There are several list I don't recall right now, that aggregate DoH services. It's not perfect, but better than nothing.