Add support for non-compliant ssh wrappers

ssh wrappers like teleport's tsh do not correctly interpret the
double dash as an argument delimiter and will not work properly
with sshuttle. This PR adds a new command line switch to handle
these cases by not adding the delimiter.

Fixes #599

docs/manpage.rst

@@ -181,6 +181,13 @@ Options
     in a non-standard location or you want to provide extra
     options to the ssh command, for example, ``-e 'ssh -v'``.
 
+.. option:: --no-cmd-delimiter
+
+    Do not add a double dash (--) delimiter before invoking Python on
+    the remote host. This option is useful when the ssh command used
+    to connect is a custom command that does not interpret this
+    delimiter correctly.
+
 .. option:: --seed-hosts
 
     A comma-separated list of hostnames to use to

sshuttle/client.py

@@ -539,7 +539,7 @@ def ondns(listener, method, mux, handlers):
 def _main(tcp_listener, udp_listener, fw, ssh_cmd, remotename,
           python, latency_control, latency_buffer_size,
           dns_listener, seed_hosts, auto_hosts, auto_nets, daemon,
-          to_nameserver):
+          to_nameserver, add_cmd_delimiter):
 
     helpers.logprefix = 'c : '
     debug1('Starting client with Python version %s'
@@ -554,6 +554,7 @@ def _main(tcp_listener, udp_listener, fw, ssh_cmd, remotename,
         (serverproc, serversock) = ssh.connect(
             ssh_cmd, remotename, python,
             stderr=ssyslog._p and ssyslog._p.stdin,
+            add_cmd_delimiter=add_cmd_delimiter,
             options=dict(latency_control=latency_control,
                          latency_buffer_size=latency_buffer_size,
                          auto_hosts=auto_hosts,
@@ -755,7 +756,7 @@ def main(listenip_v6, listenip_v4,
          latency_buffer_size, dns, nslist,
          method_name, seed_hosts, auto_hosts, auto_nets,
          subnets_include, subnets_exclude, daemon, to_nameserver, pidfile,
-         user, group, sudo_pythonpath, tmark):
+         user, group, sudo_pythonpath, add_cmd_delimiter, tmark):
 
     if not remotename:
         raise Fatal("You must use -r/--remote to specify a remote "
@@ -1103,7 +1104,7 @@ def main(listenip_v6, listenip_v4,
         return _main(tcp_listener, udp_listener, fw, ssh_cmd, remotename,
                      python, latency_control, latency_buffer_size,
                      dns_listener, seed_hosts, auto_hosts, auto_nets,
-                     daemon, to_nameserver)
+                     daemon, to_nameserver, add_cmd_delimiter)
     finally:
         try:
             if daemon:

sshuttle/cmdline.py

@@ -115,6 +115,7 @@ def main():
                                       opt.user,
                                       opt.group,
                                       opt.sudo_pythonpath,
+                                      opt.add_cmd_delimiter,
                                       opt.tmark)
 
             if return_code == 0:

sshuttle/options.py

@@ -301,6 +301,14 @@ parser.add_argument(
     the command to use to connect to the remote [%(default)s]
     """
 )
+parser.add_argument(
+    "--no-cmd-delimiter",
+    action="store_false",
+    dest="add_cmd_delimiter",
+    help="""
+    do not add a double dash before the python command
+    """
+)
 parser.add_argument(
     "--seed-hosts",
     metavar="HOSTNAME[,HOSTNAME]",

sshuttle/ssh.py

@@ -84,7 +84,7 @@ def parse_hostport(rhostport):
     return username, password, port, host
 
 
-def connect(ssh_cmd, rhostport, python, stderr, options):
+def connect(ssh_cmd, rhostport, python, stderr, add_cmd_delimiter, options):
     username, password, port, host = parse_hostport(rhostport)
     if username:
         rhost = "{}@{}".format(username, host)
@@ -183,13 +183,15 @@ def connect(ssh_cmd, rhostport, python, stderr, options):
         if password is not None:
             os.environ['SSHPASS'] = str(password)
             argv = (["sshpass", "-e"] + sshl +
-                    portl +
-                    [rhost, '--', pycmd])
+                    portl + [rhost])
 
         else:
-            argv = (sshl +
-                    portl +
-                    [rhost, '--', pycmd])
+            argv = (sshl + portl + [rhost])
+
+        if add_cmd_delimiter:
+            argv += ['--', pycmd]
+        else:
+            argv += [pycmd]
 
     # Our which() function searches for programs in get_path()
     # directories (which include PATH). This step isn't strictly