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by Bender4 hours ago |
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upvoteby scottlamb59 minutes ago|
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The article is not about abandoning ssh (client) keys but protecting them from exfiltration:

> This post documents how I’m using various secure enclaves (YubiKey, TPM, Apple Secure Enclave) to hold/encrypt SSH key material and achieve the goal of not having any unprotected key material living on-disk.

Could you help me out and state the goal of your practices as simply as this? I can guess, but I'm really not sure, especially when you get into nftables checks for window sizes.

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upvoteby Bender39 minutes ago|
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My method reduces the threat of exfiltrated keys when someone or something manages to bypass the aforementioned methods without the need to purchase anything or use anything proprietary.

- One must connect from the correct address and with the correct TCP options.

So for example I could give you one of my ssh private keys and it would be entirely useless unless you were on my home internet connection using a device that emits my TCP options. (Or this could be a corporate SNAT pool or corporate VPN pool.).

Even the most clever MitM (man in the middle) attacks become significantly harder to perform. Leaks happen, I reduce the blast radius of the damage.

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upvoteby sneak13 minutes ago|
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Just protect your keys in HSMs and all of this TCP mumbo-jumbo trying to pretend to be a secondary weak password becomes entirely unnecessary.
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upvoteby Bender9 minutes ago|
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Everyone is free to choose what options work best for their needs and budgets. I would never attempt to inhibit anyone's choices. I use what has worked well for me and stifled red-team members.
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upvoteby sneak10 seconds ago|
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Yes and you can change the protocol field in your TCP stack to run all connections over ip protocol 200 too, but it doesn’t add any security to your authentication system over and above your private key. What you are doing is the same thing; lots of extra too-clever-by-half complexity that doesn’t actually benefit you.
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upvoteby ThePowerOfFuet33 minutes ago|
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"Security by obscurity isn't."
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upvoteby Bender31 minutes ago|
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"Security by obscurity isn't."

Correct. Thankfully none of what I am doing is security through obscurity. It's actual security with a subtle scent of obscurity. If it was just obfuscation and you knew something, then you could do that something from somewhere else which you can not.

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upvoteby simgoh8 minutes ago|
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> Put the public authorized keys in /etc/ssh/keys/%u immutable, monitored for checksum changes.

Did you create your own process for monitoring/alerting on the checksum?

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upvoteby Bender8 minutes ago|
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Did you create your own process for monitoring/alerting on the checksum?

Yes, I had an LLM generate a Rust binary that performs only one function, takes up a tiny amount of memory and is hard to kill. If it is terminated it makes a lot of noise on the way out.

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