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](https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/ssh2-openssh-certkeys.html). 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 `127.0.0.1:22`

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 127.0.0.1:22?

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

**TL;DR:**

On my Ubuntu server, I want to do `ssh user@127.0.0.1` and not be asked for key or password, but only if request came from 127.0.0.1