Enabling RSA (with SHA-1) again in OpenSSH server

The sshd version that ships with Ubuntu 22.04 seems to have abandoned RSA authentication. Well, that’s not true. It’s about the hash algorithm used by the “old” protocol by the name ssh-rsa, which is deemed insecure by today’s standards. RSA is alive and kicking inside the protocols going by the names rsa-sha2–256 and rsa-sha2–512.

Either way, that caused an immediate issue with my favorite file manager on Windows: SpeedCommander ((I know some people prefer TotalCommander — but I never was much into totalitarian software 😉 and it really couldn’t deal with Unicode and long paths for a very long time — or Far Manager. That’s okay. I won’t judge. Or maybe I will, but won’t tell you the judgment 😁)).

Anyway, the solution was to enable a protocol on the server side (in my case a VM) that was understood by the client, i.e. SpeedCommander. Thus I added in /etc/ssh/sshd_config:


… restarted sshd and was happily churning on.

// Oliver

PS: I have no qualms about the use case, because it’s a VM to which I locally connect. For other use cases I would probably resort to other solutions. But then: my main system at home runs Linux, not Windows 😉

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