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.GSS_AUTH_AVAILABLE = False¶: A boolean constraint that indicates if GSS-API / SSPI is available.

paramiko.ssh_gss.GSS_EXCEPTIONS = ()¶: A tuple of the exception types used by the underlying GSSAPI implementation.

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_OLD or _SSH_GSSAPI_NEW (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_OLD (MIT GSSAPI using python-gssapi package) object, an _SSH_GSSAPI_NEW (MIT GSSAPI using gssapi package) object or an _SSH_SSPI (MS SSPI) object. 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_OLD, _SSH_GSSAPI_NEW 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

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

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
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}

__weakref__¶: list of weak references to the object (if defined)

class paramiko.ssh_gss._SSH_GSSAPI_OLD(auth_method, gss_deleg_creds)¶

Implementation of the GSS-API MIT Kerberos Authentication for SSH2, using the older (unmaintained) python-gssapi package.

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

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.

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

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

None if the MIC check was successful

Raises

gssapi.GSSException – if the MIC check failed

property credentials_delegated¶

Checks if credentials are delegated (server mode).

Returns: True if credentials are delegated, otherwise False

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_GSSAPI_NEW(auth_method, gss_deleg_creds)¶

Implementation of the GSS-API MIT Kerberos Authentication for SSH2, using the newer, currently maintained gssapi package.

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

Raises

gssapi.exceptions.GSSError if there is an error signaled by the GSS-API implementation

Returns

A String if the GSS-API has returned a token or None if no token was returned

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

str

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

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

None if the MIC check was successful

Raises

gssapi.exceptions.GSSError – if the MIC check failed

property 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

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.

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

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

None if the MIC check was successful

Raises

sspi.error – if the MIC check failed

property credentials_delegated¶

Checks if credentials are delegated (server mode).

Returns: True if credentials are delegated, otherwise False

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

GSS-API authentication¶

Paramiko

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