I am trying to satisfy a weird case, so bear with me please.

I want to use [don't gasp] graphical Windows tools (like WinSCP, PuTTY, etc) with signed OpenSSH keys. These tools don't support signed keys. But they do support a whole lot of "forwarding" and "proxy" methods.

I can set them up with a "local proxy" that actually executes OpenSSH command with the signed keys to the same server and setups up a tunnel: local port 2222 forwards to server's

Great, now the Windows tools can execute ssh/scp commands over the already-authenticated tunnel... but the first thing they try to do is: open ssh and authenticate (and they can't pass a signed key...).

So, since I already authenticated on the tunnel, can I configure the remote machine's ssh server to NOT ask nor for password, nor key, if the connection attempt is done over

Please note I am not talking about a "jump" server to reach "remote". I only have 1 "remote" server.


On my Ubuntu server, I want to do ssh user@ and not be asked for key or password, but only if request came from


You can set an empty password for the user and allow authentication with empty passwords from the localhost, by adding these lines to the top of the file /etc/ssh/sshd_config:

Match Address 127.0.0.*
  PermitEmptyPasswords yes

That makes OpenSSH accept "none" authentication:

The available authentication methods are: “gssapi-with-mic”, “hostbased”, “keyboard-interactive”, “none” (used for access to password-less accounts when PermitEmptyPasswords is enabled), “password” and “publickey”.

WinSCP and PuTTY try "none" authentication automatically. So they should not even ask for the (empty) password.

Thanks to @pa4080 for suggesting a simplification of my solution.

  • I thought that if I add match anywhere in the file, it overrides other configurations until EOF or until another match directive? – Slav Aug 26 at 13:17
  • @slav No it's the other way around, follow the first link in my answer. – Martin Prikryl Aug 26 at 13:19

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