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Descriptionifelmail@gmail.com
2022-03-29 04:03:28 UTC
Description of problem:
I'm trying to use a particular HostKeyAlgorithm - ssh-rsa-cert-v01 to connect to CentOS 9 machine (it works for C8 just fine). Both the server and client support the algorithm, however the connection fails.
In the server log, I can see this error:
Mar 28 20:19:43 <hostname.was.here> sshd[4119562]: fatal: mm_answer_sign: sign: error in libcrypto
Other protocols (at least rsa-sha2-512) work.
Version-Release number of selected component (if applicable):
openssh-server-8.7p1-8.el9.x86_64
openssl-libs-3.0.1-17.el9.x86_64
openssl-3.0.1-17.el9.x86_64
How reproducible:
Always
Steps to Reproduce:
1. [Optional, if you do not do this, the command in #2 still forces the algorithm, but if you do all ssh connections will try to use this algo and fail] On the server add to the /etc/ssh/sshd_config: "HostKeyAlgorithms ssh-rsa-cert-v01", restart the service with "systemctl restart sshd". Note, if you close the session you will not be able to ssh to the machine again.
2. On the client run: "ssh <server.name.here> -o HostKeyAlgorithms=ssh-rsa-cert-v01 'cat /etc/redhat-release'
Actual results:
Connection closed by <ip:addr::here> port 22
Expected results:
CentOS Stream release 9
Additional info:
There is a similar bug was open with OpenSSL, they suggested to open a bug with you: https://githubmemory.com/repo/openssl/openssl/issues/17963, but it seems the reporter decided to use another algo.
Comment 1Dmitry Belyavskiy
2022-03-29 07:33:13 UTC
Many thanks for your report!
ssh-rsa is an insecure nowadays signature type, the modern ones are rsa-sha2-*. We disabled support of it via libcrypto in CentOS 9, though diagnostics should be improved for clarity.
*** This bug has been marked as a duplicate of bug 2068423 ***