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Bug 2069495 - fatal: mm_answer_sign: sign: error in libcrypto - ssh-rsa-cert-v01
Summary: fatal: mm_answer_sign: sign: error in libcrypto - ssh-rsa-cert-v01@openssh.com
Keywords:
Status: CLOSED DUPLICATE of bug 2068423
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: openssh
Version: CentOS Stream
Hardware: Unspecified
OS: Linux
unspecified
high
Target Milestone: rc
: ---
Assignee: Dmitry Belyavskiy
QA Contact: BaseOS QE Security Team
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2022-03-29 04:03 UTC by ifelmail@gmail.com
Modified: 2022-03-29 11:05 UTC (History)
3 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
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Clone Of:
Environment:
Last Closed: 2022-03-29 07:33:13 UTC
Type: Bug
Target Upstream Version:
Embargoed:

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Links
System ID Private Priority Status Summary Last Updated
Red Hat Issue Tracker RHELPLAN-117064 0 None None None 2022-03-29 04:07:06 UTC

Description ifelmail@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 1 Dmitry 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 ***
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