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Requests is an HTTP library, written in Python, for human beings. This library adds optional Kerberos/GSSAPI authentication support and supports mutual authentication. Basic GET usage:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth
>>> r = requests.get("http://example.org", auth=HTTPKerberosAuth())
...The entire requests.api should be supported.
Before installing this module, the underlying Kerberos C libraries and Python development headers need to be installed. An example of how to do this for some Linux distributions is shown below:
.. code-block:: bash
# For Debian based distros
apt-get install gcc python3-dev libkrb5-dev
# For EL based distros
dnf install gcc python3-devel krb5-develThe names of the packages may vary across the distribution so use this as a general guide. MacOS and Windows users should not need these development libraries as the underlying Kerberos Python module for those platforms are provided as a wheel and the C library is already preinstalled.
While it is possible to use Kerberos authentication with an explicit
principal and password as an arg to HTTPKerberosAuth, it is
recommended to use an existing credential cache to store the credentials
instead. The credential cache can store a Kerberos Ticket-Granting Ticket
(TGT) which is then used for authentication when no password is given
to HTTPKerberosAuth. The credential cache can store a TGT by using the
kinit command and klist can be used to view the contents of the cache.
The environment variable KRB5CCNAME can be used to specify the location of
a custom credential cache.
Client authentication failures will be communicated to the caller by returning the 401 response. A 401 response may also come from an expired Ticket-Granting Ticket.
REQUIRED ^^^^^^^^
By default, HTTPKerberosAuth will require mutual authentication from the
server, and if a server emits a non-error response which cannot be
authenticated, a requests_kerberos.errors.MutualAuthenticationError will
be raised. If a server emits an error which cannot be authenticated, it will
be returned to the user but with its contents and headers stripped. If the
response content is more important than the need for mutual auth on errors,
(eg, for certain WinRM calls) the stripping behavior can be suppressed by
setting sanitize_mutual_error_response=False:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, REQUIRED
>>> kerberos_auth = HTTPKerberosAuth(mutual_authentication=REQUIRED, sanitize_mutual_error_response=False)
>>> r = requests.get("https://windows.example.org/wsman", auth=kerberos_auth)
...OPTIONAL ^^^^^^^^
If you'd prefer to not require mutual authentication, you can set your
preference when constructing your HTTPKerberosAuth object:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, OPTIONAL
>>> kerberos_auth = HTTPKerberosAuth(mutual_authentication=OPTIONAL)
>>> r = requests.get("http://example.org", auth=kerberos_auth)
...This will cause requests_kerberos to attempt mutual authentication if the
server advertises that it supports it, and cause a failure if authentication
fails, but not if the server does not support it at all.
DISABLED ^^^^^^^^
While we don't recommend it, if you'd prefer to never attempt mutual authentication, you can do that as well:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, DISABLED
>>> kerberos_auth = HTTPKerberosAuth(mutual_authentication=DISABLED)
>>> r = requests.get("http://example.org", auth=kerberos_auth)
...HTTPKerberosAuth can be forced to preemptively initiate the Kerberos
GSS exchange and present a Kerberos ticket on the initial request (and all
subsequent). By default, authentication only occurs after a
401 Unauthorized response containing a Kerberos or Negotiate challenge
is received from the origin server. This can cause mutual authentication
failures for hosts that use a persistent connection (eg, Windows/WinRM), as
no Kerberos challenges are sent after the initial auth handshake. This
behavior can be altered by setting force_preemptive=True:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, REQUIRED
>>> kerberos_auth = HTTPKerberosAuth(mutual_authentication=REQUIRED, force_preemptive=True)
>>> r = requests.get("https://windows.example.org/wsman", auth=kerberos_auth)
...If communicating with a host whose DNS name doesn't match its
kerberos hostname (eg, behind a content switch or load balancer),
the hostname used for the Kerberos GSS exchange can be overridden by
setting the hostname_override arg:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, REQUIRED
>>> kerberos_auth = HTTPKerberosAuth(hostname_override="internalhost.local")
>>> r = requests.get("https://externalhost.example.org/", auth=kerberos_auth)
...HTTPKerberosAuth normally uses the default principal (ie, the user for
whom you last ran kinit or kswitch, or an SSO credential if
applicable). However, an explicit principal can be specified, which will
cause Kerberos to look for a matching credential cache for the named user.
This feature depends on OS support for collection-type credential caches.
An explicit principal can be specified with the principal arg:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, REQUIRED
>>> kerberos_auth = HTTPKerberosAuth(principal="user@REALM")
>>> r = requests.get("http://example.org", auth=kerberos_auth)
...HTTPKerberosAuth can be used with an explicit principal and password
instead of using a credential stored in the credential cache. An explicit
username and password can be specified with the principal and password
arg respectively:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth, REQUIRED
>>> kerberos_auth = HTTPKerberosAuth(
... principal="user@REALM",
... password="SecretPassword",
...)
>>> r = requests.get("http://example.org", auth=kerberos_auth)When specifing a custom principal and password, the underlying Kerberos library will request a TGT from the KDC before using that TGT to retrieve the service ticket for authentication.
requests_kerberos supports credential delegation (GSS_C_DELEG_FLAG).
To enable delegation of credentials to a server that requests delegation, pass
delegate=True to HTTPKerberosAuth:
.. code-block:: python
>>> import requests
>>> from requests_kerberos import HTTPKerberosAuth
>>> r = requests.get("http://example.org", auth=HTTPKerberosAuth(delegate=True))
...Be careful to only allow delegation to servers you trust as they will be able to impersonate you using the delegated credentials.
This library makes extensive use of Python's logging facilities.
Log messages are logged to the requests_kerberos and
requests_kerberos.kerberos_ named loggers.
If you are having difficulty we suggest you configure logging. Issues with the underlying kerberos libraries will be made apparent. Additionally, copious debug information is made available which may assist in troubleshooting if you increase your log level all the way up to debug.
Since v0.12.0 this library automatically attempts to bind the
authentication token with the channel binding data when connecting over a TLS
connection. Channel Binding is also known as Extended Protection for
Authentication (EPA) from Microsoft. This should be ignored by servers
which do not implement support for CB but in the rare case this still fails it
can be disabled by setting send_cbt=False.