How can I use Tramp's SSH on Windows 10 with the native ssh.exe?

Question

Windows 10 has its own ssh.exe. I can use ssh.exe fine within eshell, but not for Tramp, e.g. /ssh:user@host:/tmp.

Is there any way to enable Tramp with the built-in ssh (OpenSSH_for_Windows_8.1p1, LibreSSL 3.0.2)?

Answer 1

I don't use MS Windows. However, people have reported that Tramp's sshx method works on MS Windows. Something like /sshx:user@host:/tmp.

However, it seems like you must set tramp-use-ssh-controlmaster-options to nil first, newer Tramp versions do it for you on MS Windows.

Answer 2

I can use ssh.exe fine within eshell, but not for Tramp, e.g. /ssh:user@host:/tmp.

Ah, but if you pay attention you will notice that the output in Eshell looks somewhat off:

~/ $ # within eshell
~/ $ ssh user@host
Pseudo-terminal will not be allocated because stdin is not a terminal.
...

Since no "pseudo-terminal" is allocated, the classic PS1 is missing and TRAMP does not detect the prompt. We have to adjust the login arguments.

By default, TRAMP will supply the following arguments to ssh:

(assoc 'tramp-login-args (assoc "ssh" tramp-methods))
;; => (tramp-login-args
;;     (("-l" "%u")
;;      ("-p" "%p")
;;      ("%c")
;;      ("-e" "none")
;;      ("%h")))

In order to force the allocation of a pseudo-terminal, we have to supply -tt as additional argument. I like to use cl-pushnew for that, but you may use whatever method you like (or even just setf the place):

(when (eq system-type 'windows-nt)
  (require 'cl-lib)
  (with-eval-after-load 'tramp
    (cl-pushnew '("-tt")
                (car (alist-get 'tramp-login-args
                                (cdr (assoc "ssh" tramp-methods))))
                :test #'equal)))

With this, the prompt will be shown and TRAMP can work as expected.