Return the SSH protocol specific command to connect.

def get_command(self, version=2):
        """Return the SSH protocol specific command to connect."""
        try:
            options = _C['options']
            options_str = " -o ".join(options)
            if options_str:
                options_str = "-o " + options_str + " "
        except KeyError:
            options_str = ""

        if self.username:
            # Not supported on SunOS
            # "-o ConnectTimeout={}
            command = "ssh {}" \
                      "-{} " \
                      "-p {} {}@{}".format(options_str, version, self.port, self.username, self.hostname)
        else:
            command = "ssh {} " \
                      "-{} " \
                      "-p {} {}".format(options_str, version, self.port, self.hostname)
        return command