[tptacek]

In practice, fleet operators run their own PKIs for SSH, so tying them to the DNSSEC PKI is a strict step backwards for SSH security.

There may be other applications where a global public PKI makes sense; presumably those applications will be characterized by the need to make frequent introductions between unrelated parties, which is distinctly not an attribute of the SSH problem.

[indolering]

And for everyone else that just wants to connect to an SSH session without having to setup PKI themselves? Tying that to the records used to find the domain seems like the obvious place to put that information to me!

DNSSEC lets you delegate a subtree in the namespace to a given public key. You can hardcode your DNSSEC signing key for clients too.

Don't get me started on how badly VPN PKI is handled....

[tptacek]

Yes, modern fleetwide SSH PKIs all do this; what you're describing is table stakes and doesn't involve anybody delegating any part of their security to a global PKI run by other organizations.

The WebPKI and DNSSEC run global PKIs because they routinely introduce untrusting strangers to each other. That's precisely not the SSH problem. Anything you do to bring up a new physical (or virtual) involves installing trust anchors on it; if you're in that position already, it actually harms security to have it trust a global public PKI.

The arguments for things like SSHFP and SSH-via-DNSSEC are really telling. It's like arguing that code signing certificates should be in the DNS PKI.

[indolering]

DNSSEC PKI does not preclude one from hardcoding specific keys in the client as well.

Providing global PKI and enabling end-to-end authentication by default for all clients and protocols certainly would make the internet a safer place.

[tptacek]

So now we're running two PKIs? What does the second one do? Why not three?

[indolering]

I would really appreciate it if you would respond to my points instead of just moving on to another argument.

Do you hardcode Github and AWS keys in your SSH config? Do you think it would be beneficial to global security if that happened automatically?

[tptacek]

No, we run a fleet with thousands of physicals and hundreds of thousands of virtuals, of course we don't hardcode keys in our SSH configuration. Like presumably every other large fleet operator, we solve this problem with an internal SSH CA.

Further, I haven't "moved on to another argument". Can you answer the question I just asked? If I have an existing internal PKI for my fleet, what security value is a trust relationship with DNSSEC adding? Please try to be specific, because I'm having trouble coming up with any value at all.

[throwway120385]

We also have thousands of devices accessible over SSH and we maintain our own PKI for this purpose as well. We also use mTLS with a private CA and chain of trust, for what it's worth.

It's a solved problem, basically.