The ssh_autodetect module is used to auto-detect the netmiko device_type to use to further initiate a new SSH connection with a remote host. This auto-detection is based on a unique class called SSHDetect.

Notes

The SSHDetect class is instantiated using the same parameters than a standard Netmiko connection (see the netmiko.ssh_dispatacher.ConnectHandler function). The only acceptable value for the 'device_type' argument is 'autodetect'.

The auto-detection is solely based on SSH_MAPPER_BASE. The keys are the name of the 'device_type' supported for auto-detection and the value is another dictionary describing how to handle the auto-detection.

• "cmd" : The command to send to the remote device. The command output must not require paging.
• "search_patterns" : A list of regex to compare with the output of the command
• "priority" : An integer (0-99) which specifies the confidence of the match above
• "dispatch" : The function to call to try the autodetection (per default SSHDetect._autodetect_std)

Examples

Auto-detection section

>>> from netmiko.ssh_autodetect import SSHDetect
>>> from netmiko.ssh_dispatcher import ConnectHandler
>>> remote_device = {'device_type': 'autodetect',
                     'host': 'remote.host',
                     'username': 'test',
                     'password': 'foo'}
>>> guesser = SSHDetect(**remote_device)
>>> best_match = guesser.autodetect()
>>> print(best_match) # Name of the best device_type to use further
>>> print(guesser.potential_matches) # Dictionary of the whole matching result

Netmiko connection creation section

>>> remote_device['device_type'] = best_match
>>> connection = ConnectHandler(**remote_device)

Classes

class SSHDetect (*args: Any, **kwargs: Any)

The SSHDetect class tries to automatically guess the device type running on the SSH remote end. Be careful that the kwargs 'device_type' must be set to 'autodetect', otherwise it won't work at all.

Parameters

*args : list

The same *args that you might provide to the netmiko.ssh_dispatcher.ConnectHandler.

*kwargs : dict

The same *kwargs that you might provide to the netmiko.ssh_dispatcher.ConnectHandler.

Attributes

connection : TerminalServerSSH

A basic connection to the remote SSH end.

potential_matches : dict

Dict of (device_type, accuracy) that is populated through an interaction with the remote end.

Methods

autodetect() Try to determine the device type.

Constructor of the SSHDetect class

Expand source code

class SSHDetect(object):
    """
    The SSHDetect class tries to automatically guess the device type running on the SSH remote end.
    Be careful that the kwargs 'device_type' must be set to 'autodetect', otherwise it won't work at
    all.

    Parameters
    ----------
    *args : list
        The same *args that you might provide to the netmiko.ssh_dispatcher.ConnectHandler.
    *kwargs : dict
        The same *kwargs that you might provide to the netmiko.ssh_dispatcher.ConnectHandler.

    Attributes
    ----------
    connection : netmiko.terminal_server.TerminalServerSSH
        A basic connection to the remote SSH end.
    potential_matches: dict
        Dict of (device_type, accuracy) that is populated through an interaction with the
        remote end.

    Methods
    -------
    autodetect()
        Try to determine the device type.
    """

    def __init__(self, *args: Any, **kwargs: Any) -> None:
        """
        Constructor of the SSHDetect class
        """
        if kwargs["device_type"] != "autodetect":
            raise ValueError("The connection device_type must be 'autodetect'")
        # Always set cmd_verify to False for autodetect
        kwargs["global_cmd_verify"] = False
        self.connection = ConnectHandler(*args, **kwargs)

        # Add additional sleep to let the login complete.
        time.sleep(3)

        # Call the _test_channel_read() in base to clear initial data
        output = BaseConnection._test_channel_read(self.connection)
        self.initial_buffer = output
        self.potential_matches: Dict[str, int] = {}
        self._results_cache: Dict[str, str] = {}

    def autodetect(self) -> Union[str, None]:
        """
        Try to guess the best 'device_type' based on patterns defined in SSH_MAPPER_BASE

        Returns
        -------
        best_match : str or None
            The device type that is currently the best to use to interact with the device
        """
        for device_type, autodetect_dict in SSH_MAPPER_BASE:
            tmp_dict = autodetect_dict.copy()
            call_method = tmp_dict.pop("dispatch")
            assert isinstance(call_method, str)
            autodetect_method = getattr(self, call_method)
            accuracy = autodetect_method(**tmp_dict)
            if accuracy:
                self.potential_matches[device_type] = accuracy
                if accuracy >= 99:  # Stop the loop as we are sure of our match
                    best_match = sorted(
                        self.potential_matches.items(), key=lambda t: t[1], reverse=True
                    )
                    # WLC needs two different auto-dectect solutions
                    if "cisco_wlc_85" in best_match[0]:
                        best_match[0] = ("cisco_wlc", 99)
                    # IOS XR needs two different auto-dectect solutions
                    if "cisco_xr_2" in best_match[0]:
                        best_match[0] = ("cisco_xr", 99)
                    self.connection.disconnect()
                    return best_match[0][0]

        if not self.potential_matches:
            self.connection.disconnect()
            return None

        best_match = sorted(
            self.potential_matches.items(), key=lambda t: t[1], reverse=True
        )
        self.connection.disconnect()
        return best_match[0][0]

    def _send_command(self, cmd: str = "") -> str:
        """
        Handle reading/writing channel directly. It is also sanitizing the output received.

        Parameters
        ----------
        cmd : str, optional
            The command to send to the remote device (default : "", just send a new line)

        Returns
        -------
        output : str
            The output from the command sent
        """
        self.connection.write_channel(cmd + "\n")
        time.sleep(1)
        output = self.connection.read_channel_timing(last_read=6.0)
        output = self.connection.strip_backspaces(output)
        return output

    def _send_command_wrapper(self, cmd: str) -> str:
        """
        Send command to the remote device with a caching feature to avoid sending the same command
        twice based on the SSH_MAPPER_BASE dict cmd key.

        Parameters
        ----------
        cmd : str
            The command to send to the remote device after checking cache.

        Returns
        -------
        response : str
            The response from the remote device.
        """
        cached_results = self._results_cache.get(cmd)
        if not cached_results:
            response = self._send_command(cmd)
            self._results_cache[cmd] = response
            return response
        else:
            return cached_results

    def _autodetect_remote_version(
        self,
        search_patterns: Optional[List[str]] = None,
        re_flags: int = re.IGNORECASE,
        priority: int = 99,
        **kwargs: Any
    ) -> int:
        """
        Method to try auto-detect the device type, by matching a regular expression on the reported
        remote version of the SSH server.

        Parameters
        ----------
        search_patterns : list
            A list of regular expression to look for in the reported remote SSH version
            (default: None).
        re_flags: re.flags, optional
            Any flags from the python re module to modify the regular expression (default: re.I).
        priority: int, optional
            The confidence the match is right between 0 and 99 (default: 99).
        """
        invalid_responses = [r"^$"]

        if not search_patterns:
            return 0

        try:
            remote_conn = self.connection.remote_conn
            assert isinstance(remote_conn, paramiko.Channel)
            assert remote_conn.transport is not None
            remote_version = remote_conn.transport.remote_version
            for pattern in invalid_responses:
                match = re.search(pattern, remote_version, flags=re.I)
                if match:
                    return 0
            for pattern in search_patterns:
                match = re.search(pattern, remote_version, flags=re_flags)
                if match:
                    return priority
        except Exception:
            return 0
        return 0

    def _autodetect_std(
        self,
        cmd: str = "",
        search_patterns: Optional[List[str]] = None,
        re_flags: int = re.IGNORECASE,
        priority: int = 99,
    ) -> int:
        """
        Standard method to try to auto-detect the device type. This method will be called for each
        device_type present in SSH_MAPPER_BASE dict ('dispatch' key). It will attempt to send a
        command and match some regular expression from the ouput for each entry in SSH_MAPPER_BASE
        ('cmd' and 'search_pattern' keys).

        Parameters
        ----------
        cmd : str
            The command to send to the remote device after checking cache.
        search_patterns : list
            A list of regular expression to look for in the command's output (default: None).
        re_flags: re.flags, optional
            Any flags from the python re module to modify the regular expression (default: re.I).
        priority: int, optional
            The confidence the match is right between 0 and 99 (default: 99).
        """
        invalid_responses = [
            r"% Invalid input detected",
            r"syntax error, expecting",
            r"Error: Unrecognized command",
            r"%Error",
            r"command not found",
            r"Syntax Error: unexpected argument",
            r"% Unrecognized command found at",
        ]
        if not cmd or not search_patterns:
            return 0
        try:
            # _send_command_wrapper will use already cached results if available
            response = self._send_command_wrapper(cmd)
            # Look for error conditions in output
            for pattern in invalid_responses:
                match = re.search(pattern, response, flags=re.I)
                if match:
                    return 0
            for pattern in search_patterns:
                match = re.search(pattern, response, flags=re_flags)
                if match:
                    return priority
        except Exception:
            return 0
        return 0

Methods

def autodetect(self) ‑> Optional[str]

Try to guess the best 'device_type' based on patterns defined in SSH_MAPPER_BASE

Returns

best_match : str or None

The device type that is currently the best to use to interact with the device