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# GSS-API authentication

This module provides GSS-API / SSPI authentication as defined in RFC 4462.

Note

Credential delegation is not supported in server mode.

See also

GSS-API key exchange

New in version 1.15.

`paramiko.ssh_gss.``GSSAuth`(auth_method, gss_deleg_creds=True)

  Provide SSH2 GSS-API / SSPI authentication.

  Parameters: | auth_method (str) – The name of the SSH authentication mechanism (gssapi-with-mic or gss-keyex) gss_deleg_creds (bool) – Delegate client credentials or not. We delegate credentials by default.
  Returns: | Either an `_SSH_GSSAPI` (Unix) object or an `_SSH_SSPI` (Windows) object
  Return type: | Object
  Raises ImportError:
  | If no GSS-API / SSPI module could be imported.
  See: | RFC 4462
  Note: | Check for the available API and return either an `_SSH_GSSAPI` (MIT GSSAPI) object or an `_SSH_SSPI` (MS SSPI) object. If you get python-gssapi working on Windows, python-gssapi will be used and a `_SSH_GSSAPI` object will be returned. If there is no supported API available, `None` will be returned.

class `paramiko.ssh_gss.``_SSH_GSSAuth`(auth_method, gss_deleg_creds)

  Contains the shared variables and methods of `_SSH_GSSAPI` and `_SSH_SSPI`.

  `__init__`(auth_method, gss_deleg_creds)

    Parameters: | auth_method (str) – The name of the SSH authentication mechanism (gssapi-with-mic or gss-keyex) gss_deleg_creds (bool) – Delegate client credentials or not

  `set_service`(service)

    This is just a setter to use a non default service. I added this method, because RFC 4462 doesn’t specify “ssh-connection” as the only service value.

    Parameters: | service (str) – The desired SSH service
    Return type: | Void

  `set_username`(username)

    Setter for C{username}. If GSS-API Key Exchange is performed, the username is not set by C{ssh_init_sec_context}.

    Parameters: | username (str) – The name of the user who attempts to login
    Return type: | Void

  `ssh_gss_oids`(mode='client')

    This method returns a single OID, because we only support the Kerberos V5 mechanism.

    Parameters: | mode (str) – Client for client mode and server for server mode
    Returns: | A byte sequence containing the number of supported OIDs, the length of the OID and the actual OID encoded with DER
    Return type: | Bytes
    Note: | In server mode we just return the OID length and the DER encoded OID.

  `ssh_check_mech`(desired_mech)

    Check if the given OID is the Kerberos V5 OID (server mode).

    Parameters: | desired_mech (str) – The desired GSS-API mechanism of the client
    Returns: | `True` if the given OID is supported, otherwise C{False}
    Return type: | Boolean

  `__weakref__`

    list of weak references to the object (if defined)

class `paramiko.ssh_gss.``_SSH_GSSAPI`(auth_method, gss_deleg_creds)

  Implementation of the GSS-API MIT Kerberos Authentication for SSH2.

  See: | `GSSAuth`

  `__init__`(auth_method, gss_deleg_creds)

    Parameters: | auth_method (str) – The name of the SSH authentication mechanism (gssapi-with-mic or gss-keyex) gss_deleg_creds (bool) – Delegate client credentials or not

  `ssh_init_sec_context`(target, desired_mech=None, username=None, recv_token=None)

    Initialize a GSS-API context.

    Parameters: | username (str) – The name of the user who attempts to login target (str) – The hostname of the target to connect to desired_mech (str) – The negotiated GSS-API mechanism (“pseudo negotiated” mechanism, because we support just the krb5 mechanism :-)) recv_token (str) – The GSS-API token received from the Server
    Raises SSHException:
    | Is raised if the desired mechanism of the client is not supported
    Returns: | A `String` if the GSS-API has returned a token or `None` if no token was returned
    Return type: | String or None

  `ssh_get_mic`(session_id, gss_kex=False)

    Create the MIC token for a SSH2 message.

    Parameters: | session_id (str) – The SSH session ID gss_kex (bool) – Generate the MIC for GSS-API Key Exchange or not
    Returns: | gssapi-with-mic: Returns the MIC token from GSS-API for the message we created with `_ssh_build_mic`. gssapi-keyex: Returns the MIC token from GSS-API with the SSH session ID as message.
    Return type: | String
    See: | `_ssh_build_mic`

  `ssh_accept_sec_context`(hostname, recv_token, username=None)

    Accept a GSS-API context (server mode).

    Parameters: | hostname (str) – The servers hostname username (str) – The name of the user who attempts to login recv_token (str) – The GSS-API Token received from the server, if it’s not the initial call.
    Returns: | A `String` if the GSS-API has returned a token or `None` if no token was returned
    Return type: | String or None

  `ssh_check_mic`(mic_token, session_id, username=None)

    Verify the MIC token for a SSH2 message.

    Parameters: | mic_token (str) – The MIC token received from the client session_id (str) – The SSH session ID username (str) – The name of the user who attempts to login
    Returns: | 0 if the MIC check was successful and 1 if it fails
    Return type: | int

  `credentials_delegated`

    Checks if credentials are delegated (server mode).

    Returns: | `True` if credentials are delegated, otherwise `False`
    Return type: | bool

  `save_client_creds`(client_token)

    Save the Client token in a file. This is used by the SSH server to store the client credentials if credentials are delegated (server mode).

    Parameters: | client_token (str) – The GSS-API token received form the client
    Raises NotImplementedError:
    | Credential delegation is currently not supported in server mode

class `paramiko.ssh_gss.``_SSH_SSPI`(auth_method, gss_deleg_creds)

  Implementation of the Microsoft SSPI Kerberos Authentication for SSH2.

  See: | `GSSAuth`

  `__init__`(auth_method, gss_deleg_creds)

    Parameters: | auth_method (str) – The name of the SSH authentication mechanism (gssapi-with-mic or gss-keyex) gss_deleg_creds (bool) – Delegate client credentials or not

  `ssh_init_sec_context`(target, desired_mech=None, username=None, recv_token=None)

    Initialize a SSPI context.

    Parameters: | username (str) – The name of the user who attempts to login target (str) – The FQDN of the target to connect to desired_mech (str) – The negotiated SSPI mechanism (“pseudo negotiated” mechanism, because we support just the krb5 mechanism :-)) recv_token – The SSPI token received from the Server
    Raises SSHException:
    | Is raised if the desired mechanism of the client is not supported
    Returns: | A `String` if the SSPI has returned a token or `None` if no token was returned
    Return type: | String or None

  `ssh_get_mic`(session_id, gss_kex=False)

    Create the MIC token for a SSH2 message.

    Parameters: | session_id (str) – The SSH session ID gss_kex (bool) – Generate the MIC for Key Exchange with SSPI or not
    Returns: | gssapi-with-mic: Returns the MIC token from SSPI for the message we created with `_ssh_build_mic`. gssapi-keyex: Returns the MIC token from SSPI with the SSH session ID as message.
    Return type: | String
    See: | `_ssh_build_mic`

  `ssh_accept_sec_context`(hostname, username, recv_token)

    Accept a SSPI context (server mode).

    Parameters: | hostname (str) – The servers FQDN username (str) – The name of the user who attempts to login recv_token (str) – The SSPI Token received from the server, if it’s not the initial call.
    Returns: | A `String` if the SSPI has returned a token or `None` if no token was returned
    Return type: | String or None

  `ssh_check_mic`(mic_token, session_id, username=None)

    Verify the MIC token for a SSH2 message.

    Parameters: | mic_token (str) – The MIC token received from the client session_id (str) – The SSH session ID username (str) – The name of the user who attempts to login
    Returns: | 0 if the MIC check was successful
    Return type: | int

  `credentials_delegated`

    Checks if credentials are delegated (server mode).

    Returns: | `True` if credentials are delegated, otherwise `False`
    Return type: | Boolean

  `save_client_creds`(client_token)

    Save the Client token in a file. This is used by the SSH server to store the client credentails if credentials are delegated (server mode).

    Parameters: | client_token (str) – The SSPI token received form the client
    Raises NotImplementedError:
    | Credential delegation is currently not supported in server mode