Issues with newest version of openssh 8.8p1-1

Updated to openssh (8.8p1-1) and git didn't get the keys anymore. Couldn't pull or push. After reverting back to 8.7p1-2 it works as intended.

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What did you do before the bug happened? (Steps to reproduce your issue) Updated system packages (openssh) What did you expect to happen? (Expected behavior) Can git pull without issues What happened instead? (Actual behavior) Permission Denied due to key error What's different between what you expected and what actually happened? I couldn't push pull whatever because the keys haven't been recognized somehow Anything else you want to add: I reverted from openssh 8.8p1-1 to 8.7p1-2 to make it work again Please review the rest of the bug report below. You can delete any lines you don't wish to share.

[System Info] git version 2.33.0 cpu: x86_64 no commit associated with this build sizeof-long: 8 sizeof-size_t: 8 shell-path: /bin/sh uname: Linux 5.14.8-arch1-1 #1 SMP PREEMPT Sun, 26 Sep 2021 19:36:15 +0000 x86_64 compiler info: gnuc: 11.1 libc info: glibc: 2.33 $SHELL (typically, interactive shell): /bin/bash

[Enabled Hooks]

On Mon, Sep 27, 2021 at 11:40 PM Kevin Kendzia <kevin.kendzia@googlemail.com> wrote:

Ultimately this isn't a Git issue; it's an SSH issue. My guess would be that upgrading to OpenSSH 8.8 picks up the change to stop using RSA signatures using SHA-1 hashes by default.[1]

You can update your ~/.ssh/config to add these lines to revert that
and allow using those keys again:
Host old-host
     HostkeyAlgorithms +ssh-rsa
     PubkeyAcceptedAlgorithms +ssh-rsa

With that said, though, if possible a better solution is to generate new SSH keys using ECDSA, Ed25519 or another stronger signature and switch to those.

Hope this helps! Bryan

[1] https://www.openssh.com/releasenotes.html

On 2021-09-28 at 07:32:05, Bryan Turner wrote:

I should point out that these algorithms are disabled by default because they are a security risk. This has been announced for a long time now in OpenSSH and everyone should have either switched key types or enabled RSA with SHA-2 or both.

You also need to contact the party operating the server to which you're trying to push in this case, since it's ultimately the fact that they don't support RSA with SHA-2 that's the problem.

There are a couple different providers (in my testing just this second, I found Bitbucket and Azure DevOps) who are still offering only the ssh-rsa host keys (possibly with ssh-dss as well) and not offering the rsa-sha2-256 and rsa-sha2-512 algorithms, and only the server operator can fix those. If the server operator adds support for RSA with SHA-2, then OpenSSH 8.8 will work just fine. But otherwise, this will continue to be broken out of the box.

But as for client keys, I do strongly recommend Ed25519 in all cases. If you have the misfortune of having to use a FIPS-compliant environment (which I don't recommend in any case), then use RSA with SHA-2.

Something like `ssh -vvv user@host` would probably be useful to see where the key negotiation breaks for you, but it is unlikely to be a problem with git.

My guess is that your host key is still using RSA with SHA1 and you haven't updated it by following the instructions[1] OpenSSH provided with their 8.3 release

Carlo

PS. I upgraded to OpenSSH 8.8p1 and had no problems connecting, but I am not on Arch, so that might be another possibility

[1] https://lwn.net/Articles/821544/

On 28/09/21 13.40, Kevin Kendzia wrote:

What remote you tried to push or pull from? What key do you use? If you're connecting to GitHub, see [1].

[1]: https://github.blog/2021-09-01-improving-git-protocol-security-github/