On a Linux 8 system with FIPS enabled, connecting to a Linux 6 system fails, ssh -v displays the following message
ssh_dispatch_run_fatal: Connection to XXX port 22: invalid argument
Solution
The simplest solution is to delete file /etc/ssh/moduli on the Linux 6 system serving as sshd backend.
The same workaround is applicable for other Linux 8 FIPS clients connecting to non-FIPS servers using this key exchange method.
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