To ssh, the server I am connecting to needs a password followed by an RSA-like key.

It goes:

Verification code:

I've read Tramp with 2-factor authentication, but it does not solve the problem completely.

I've appended "Verification code" into tramp-password-prompt-regexp.

But what happens when I try to login is that I get an opportunity to put in my password, and then I see:

Tramp: Sending Password
Tramp: Sending Verification code
Tramp: Sending Password
Tramp: Sending Verification code
Tramp: Sending Password
Tramp: Sending Verification code
Tramp: Waiting for prompts from remote shell...failed

Before it eventually fails. I feel like it's treating Verification code and Password as one and the same, and instead of prompting me for a Verification code, it just goes ahead and sends the password.

How do I get tramp to prompt a second time for the verification code? I want it to collect a second read-string from the user or something.

  • What happens, if you disable password caching? Let's say, try (setq password-cache nil). – Michael Albinus Oct 21 '15 at 19:29
  • That was a good idea. I was able to enter in my verification code. I then got the following error however. unix_listener: "/var/folders/jy/__string__/T/tramp.__string__.__username@domain__:22.__string__" too long for Unix domain socket – bernie Oct 21 '15 at 19:45
  • Yes, this is a known problem in Tramp reported as Emacs bugs 19702 and 21374. Solved (likely) in Emacs 24.5, solved for sure in Emacs 25.0.50 (the development version of Emacs). – Michael Albinus Oct 22 '15 at 8:10
  • I updated to 25.5.1 and I was able to login. Very cool feature. Thanks! – bernie Oct 22 '15 at 14:56

Solution (per Michael Albinus, above) for 2-factor authentication in Tramp:

  • upgrade Emacs to 24.5 or use Emacs development version 25.0.50 or later

Also see related answer.

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