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.

1 files changed, 6 insertions, 10 deletions

diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index dbf46794a82..fbb5d8c6349 100644
--- 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")