Subject: bug#21504: (require 'tramp) stuck on testing `tramp-ssh-controlmaster-options'

From: Michael Albinus <[email-masked]>
Date: Thu, 17 Sep 2015 20:56:54 +0200

傅文辉 <[email-masked]> writes:

> Emacs 24.5.1, tramp 2.2.11-24.5
>
> The following code stuck with some DNS settings
>
>>>> file: tramp-loaddefs.el
> (defvar tramp-ssh-controlmaster-options
>   ...
>   (call-process "ssh" nil t nil "-o" "ControlPath=%C" "host.does.not.exist")
>   ...)
> <<<
>
> `ssh -o ControlPath=%C host.does.not.exist` stuck instead of going
> error quickly with DNS from my ISP (both home and workplace).

It is a similar bug report like bug#20015. Solved in Emacs 25 (the git
version), using 0.0.0.1 as not existing host. This avoids problems with
improper DNS settings.

Best regards, Michael.