Re: [DNSOP] Draft for dynamic discovery of secure resolvers

Craig Finseth <snark17@gmail.com> Sun, 19 August 2018 17:20 UTC

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From: Craig Finseth <snark17@gmail.com>
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Date: Sun, 19 Aug 2018 12:20:53 -0500
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To: Doug Barton <dougb@dougbarton.us>
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Subject: Re: [DNSOP] Draft for dynamic discovery of secure resolvers
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Or, you have malware trying to bypass DNS checks.

Craig Finseth 

> On Aug 19, 2018, at 11:43, Doug Barton <dougb@dougbarton.us> wrote:
> 
>> On 08/18/2018 06:08 PM, Ted Lemon wrote:
>> The thing is that most devices don't connect to just one network.   So while your devices on your network can certainly trust port 853 on your network, when they roam to other networks, they have no reason to trust it.   If you have devices that never roam to other networks, that's fine, but we have to design for the more general case.   There's no way with DHCP for the device to tell that it's connected to a particular network, other than matching IP addresses, which isn't a great idea.
> 
> Ted,
> 
> I'd like to turn your question back to you. What threat model are you protecting the user from by not allowing a DHCP option to use a DOH or DOT server?
> 
> It seems to me that in the overwhelming majority of cases (near 100%) the user is going to get their local resolver from the DHCP server, whether they are on a trusted network (like work or home), or roaming at Eve's Coffee Shop.
> 
> So either you have a sophisticated user who has preconfigured their own resolver and ignores the DHCP setting, or you have the typical user who doesn't understand how any of this stuff works, and therefore has implicit "trust" regarding the local network and the settings from the DHCP server.
> 
> Given that (and feel free to tell me if I've missed something), what harm can come to the user if the resolver that they are already trusting can also be accessed over DOH or DOT?
> 
> Doug
> 
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