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Comment by tptacek | Hacker News Reader

How does securing DNS lookups solve the MITM problem if the underlying traffic remains unencrypted? If you encrypt the traffic, you don't need secure DNS anymore.

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That depends on what your trust model is. Somebody is resolving the DNS query, and then the result gets transmitted to you. If all you're worried about the result being MITM'd during transit, then encryption is sufficient. You can set up DNSCrypt to deal with this today [1].

But often the provider resolving the query is itself untrustworthy. Most providers these days (including OpenDNS) redirect invalid queries to their own landing pages (which poisons caches and has other bad effects). Providers may "censor" certain domains. Or be subverted by state-level actors (see: Belgacom). In DNSSEC, the root of trust is the administrator of the DNS root zone (e.g., Verisign, whom you're probably already trusting anyway).

[1] But encryption is not a panacea. As soon as you visit the address(es) returned, someone will get a pretty good idea what you looked up.

It doesn't matter if you can MITM someone through the DNS. Stipulate that it's trivial to do that. You still can't get in the middle of my SSH connection, because SSH authenticates itself, bidirectionally.

In that case, DNSSEC probably isn't doing much for you (besides the systemic effects of discouraging providers from returning false DNS results in the first place), but sadly not everything on the internet is so well-designed as ssh. Being unable to specify a port in MX records, leaving SMTP on port 25 with only STARTTLS for encryption being one good example.

> Most providers these days (including OpenDNS) redirect invalid queries to their own landing pages

OpenDNS stopped doing this on June 6 2014:

http://blog.opendns.com/2014/05/29/no-more-ads/

OpenDNS could still turn ads on again at any time. And the censorship and subversion arguments are still valid.

Something about which I'm glad to be wrong.

The DNS traffic doesn't need to be secret ("encrypted"), it just needs to be authenticated (i.e. the payload has not been modified and there is a chain of trust).

If a client is pre-seeded with trusted root keys, DNSSEC protected payload can be validated to the apex.

If traffic is end-to-end protected with cryptography --- as, for instance, it is in the SSH protocol --- why does it matter if DNS records are authenticated? If you forge a DNS record, the SSH protocol will kill the session. SSH doesn't even need to care what the DNS says; all that matters are the cryptographic secrets.

I'm going to be generous here and assume they meant authenticated encryption rather than just encryption between the user and the first DNS server they hit.

Which, given how DNSCurve was designed, is a non sequitur :)

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