Windows 10 SSH client: password-less access

As an addition to the answer by Thomas S., I found a way Windows can remember the passphrase, even after reboot. This uses PowerShell.

Run this in an elevated PowerShell Session (= run as admin):

Get-Service ssh-agent | Set-Service -StartupType Automatic -PassThru | Start-Service

(Or you can do that with the GUI if you know how. It basically makes the ssh-agent start automatically.)

Optional for Git

In order to make Git recognize all these settings, you need to tell Git to use the internal OpenSSH instead of its own. (Yes, in case of Git there are two OpenSSH instances now)

git config --global core.sshCommand C:/Windows/System32/OpenSSH/ssh.exe

(Use forward-slashes / or double backslashes \\ in this path)

By doing that also Git (including all Git clients) has access to the stored passphrase.

Source: https://github.com/dahlbyk/posh-git/issues/640#issuecomment-435515055

• be sure the optional Windows feature "OpenSSH Client" is installed
• ensure the service "OpenSSH Authentication Agent" has at least the "manual" startup type (by default: disabled)
• start the service, e.g. by invoking ssh-agent
• tell it about the private key file: ssh-add <path-to-private-key-file>
• now ssh user@server works without asking for the passphrase

Unfortunately, I have not found a way to let it remember the private key and passphrase after reboot.