use default ssh tunnel for localhost Controller on remote machine

also change error message when paramiko is unavailable, so we don't instruct Windows users to 'use openssh'.

IPython/external/ssh/tunnel.py

@@ -81,7 +81,12 b' def _try_passwordless_openssh(server, keyfile):'
 def _try_passwordless_paramiko(server, keyfile):
     """Try passwordless login with paramiko."""
     if paramiko is None:
-        raise ImportError("paramiko unavailable, use openssh")
+        msg = "Paramiko unavaliable, "
+        if sys.platform == 'win32':
+            msg += "Paramiko is required for ssh tunneled connections on Windows."
+        else:
+            msg += "use OpenSSH."
+        raise ImportError(msg)
     username, server, port = _split_server(server)
     client = paramiko.SSHClient()
     client.load_system_host_keys()

IPython/parallel/client/client.py

@@ -32,6 +32,7 b' from IPython.config.configurable import MultipleInstanceError'
 from IPython.core.application import BaseIPythonApplication
 
 from IPython.utils.jsonutil import rekey
+from IPython.utils.localinterfaces import LOCAL_IPS
 from IPython.utils.path import get_ipython_dir
 from IPython.utils.traitlets import (HasTraits, Int, Instance, Unicode,
                                     Dict, List, Bool, Set)
@@ -322,6 +323,14 b' class Client(HasTraits):'
         location = cfg.setdefault('location', None)
         cfg['url'] = util.disambiguate_url(cfg['url'], location)
         url = cfg['url']
+        if location is not None:
+            proto,addr,port = util.split_url(url)
+            if addr == '127.0.0.1' and location not in LOCAL_IPS and not sshserver:
+                sshserver = location
+                warnings.warn(
+                    "Controller appears to be listening on localhost, but is not local. "
+                    "IPython will try to use SSH tunnels to %s"%location,
+                    RuntimeWarning)
         
         self._config = cfg