I have a 2013 MacBook Pro that's been maxed out at MacOS 10.15.7 (19H2026) for quite a while now. It's configured to accept password-less SSH connections. A couple of days ago, out of the blue, when I try to SSH in, it began prompting for a password. I am connecting to the 2013 MacBook Pro with a...
Try editing the ~/.ssh/known_hosts on the MacBook Air to remove the MacBook Pro and then try again. It might be an encoding scheme issue with the older SSH on the MacBook Pro and newer SSH on the MacBook Air.
I noticed earlier today that on the MacBook Air, the default for ssh-keygen is to generate an 'ed25519' public/private key pair by default now, rather than RSA. Wondering if this is relevant.
@Giacomo1968 - don't remember when I applied 14.2.1. I ssh from Air to Pro multiple times a day, first saw problem yesterday and am pretty sure last OS update was more than a couple of days ago (any way to check?)
@Giacomo1968 - update#2 has been added. Problem still occurring after adding .ssh/config (mode 644).
Sorry the answer didn’t seem to help. To check when updates happened on macOS, go to “About This Mac” then choose “More Info…” and then scroll down to see “System Report…” then scroll to “Software > Installations” and you can then see a list of items installed and you can sort by “Install Date.”
Updated my answer with one last “Hail Mary” for setting PubkeyAcceptedKeyTypes in ~/.ssh/config. Try that and see if it works. If not? I’ve done my best! Sorry. Maybe the best thing to do is to update things to use ed25519 as suggested here. I dunno. Good luck!
@Giacomo1968 - thanks for your efforts! Will take another look in the morning -- including learning to read the verbose ssh output, and investigating ed25519 which sounds like a likely culprit.
I have the exact same issue when trying to SSH from a M2 MacBook Pro into an Intel Mac Mini, both running Sonoma. No problem when I SSH from the Mac Mini to the MacBook Pro.
According to the debug output, the Air offered both id_rsa and id_ecdsa to the Pro, and the Pro didn't accept them. Have you checked permissions for your home directory, .ssh directory, and .ssh/authorized_keys on the Pro?
NB where you say "Permissions on ~/.ssh (600)", permissions on ~/.ssh should be 700, in other words the "x" permission should also be on.
Well, at least you solved the issue and learned a few things along the way. Happy to have helped! I did take my comment advising on how to check for system updates and made it a self-answered question.
@Kenster - if I'd read your post more carefully I'd have seen you mentioned home directory permissions, which turned out to be the problem (777 rather than 755). Since I made that change a year or two ago, I'm unable to explain why it just recently began to be a problem for ssh.
Discussion on question by Chap: MacOS…
Discussion on question by Chap: MacOS…