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0 pointsReelin5y ago0 comments

> there continue to be threads full of arguments that amount to "It should be possible for 'good' network admins to intercept traffic from devices that don't trust them, but 'bad' network admins shouldn't be able to intercept traffic from devices that don't trust them"

That's not what I see at all.

I see people pointing out that DoH hurts privacy and reduces control for end users by providing a convenient turnkey solution for device vendors to bypass filtering at the network level.

I also see it pointed out that DoH could have been specified in a way that facilitated filtering for the local network. Given that it's so obviously possible, the fact that it wasn't speaks volumes.

Note that (IIUC) your ISP can still see which sites you visit because TLS still transmits the FQDN in plaintext (https://security.stackexchange.com/questions/86723). Even if that stopped happening tomorrow, the destination IP would still be visible (not quite as bad but still reveals a huge amount of information). On top of all that, DNSSEC already exists which allows you to verify the authenticity of the query result. As such, the argument in favor of DoH would seem to be limited to preventing your DNS resolver (but not your ISP or VPN!) from tracking which sites you visit. I don't find that to be very compelling in light of the immediate downsides.

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JoshTriplett5y ago

> I also see it pointed out that DoH could have been specified in a way that facilitated filtering for the local network. Given that it's so obviously possible

No, it couldn't have been, and this is exactly what I was referring to in my comment. Any mechanism that allows the local network to intercept the traffic of a device that doesn't trust the network can and will be abused. The entire point of DoH was to make DNS clients secure, by preventing ISPs and other network providers from monitoring, intercepting, or tampering with DNS results.

You're asking for DNS to be left insecure, so that you can tamper with it. You're asking for the security of clients that actually give users control (laptops, phones, etc) to be sacrificed so that you can continue to tamper with DNS results for clients that don't give users control.

> On top of all that, DNSSEC already exists which allows you to verify the authenticity of the query result.

DNSSEC isn't nearly widespread enough to expect to find it everywhere. Only very specialized clients could make it a requirement; most clients cannot. DNSSEC requires upgrading most of the world before people can rely on it; DoH is an incremental solution.

> As such, the argument in favor of DoH would seem to be limited to preventing your DNS resolver (but not your ISP or VPN!) from tracking which sites you visit.

SNI is being fixed. Once SNI is fixed, DNS is one of the last holes that allows your ISP or other network provider to track you.

And as mentioned above, since DNSSEC is not a viable solution anytime soon, DoH is also critically important to prevent ISPs and other network providers to tamper with your DNS results.

tptacek5y ago

Some color to this: it's less than 2% of North American domains, the number of signed zones has actually dropped in some intervals, and it's practically nonexistent among big companies with security teams. Google isn't DNSSEC-signed. Neither is Microsoft. Or Facebook. Or Amazon (whose DNS service, Route53, doesn't implement DNSSEC). Or, last I checked, any US bank.

You can check this for yourself: make a list of domains, and then write a trivial script:

    #!/bin/sh
    while read domain
    do 
      ds=$(dig ds $domain +short)
      echo "$domain $ds"
    done

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