Use 0.0.0.1 as test host in Tramp

* lisp/net/tramp-sh.el (tramp-ssh-controlmaster-options):
Use 0.0.0.1 as test host.

diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index dbf46794a822d5e814b58ce92100bca92f7737b7..fbb5d8c6349459fa684dea17ee09669ba25ae2aa 100644 (file)
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -4614,19 +4614,15 @@ Gateway hops are already opened."
                (setq tramp-ssh-controlmaster-options "-o ControlMaster=auto")))
            (unless (zerop (length tramp-ssh-controlmaster-options))
              (with-temp-buffer
-               ;; When we use a non-existing host name, we could run
-               ;; into DNS timeouts.  So we use "localhost" with an
-               ;; improper port, expecting nobody runs sshd on the
-               ;; telnet port.
+               ;; We use a non-existing IP address, in order to avoid
+               ;; useless connections, and DNS timeouts.
                (tramp-call-process
-                vec "ssh" nil t nil
-                "-p" "23" "-o" "ControlPath=%C" "localhost")
+                vec "ssh" nil t nil "-o" "ControlPath=%C" "0.0.0.1")
                (goto-char (point-min))
                (setq tramp-ssh-controlmaster-options
-                     (if (search-forward-regexp "unknown.+key" nil t)
-                         (concat tramp-ssh-controlmaster-options
-                                 " -o ControlPath='tramp.%%r@%%h:%%p'")
-                       (concat tramp-ssh-controlmaster-options
+                     (concat tramp-ssh-controlmaster-options
+                             (if (search-forward-regexp "unknown.+key" nil t)
+                                 " -o ControlPath='tramp.%%r@%%h:%%p'"
                                " -o ControlPath='tramp.%%C'"))))
              (with-temp-buffer
                (tramp-call-process vec "ssh" nil t nil "-o" "ControlPersist")