Kerberos authentication for Django
==================================

Provide Kerberos authentication to Django applications.

Basic usage
===========

Add this to your project `urls.py`::

    url('^accounts/kerberos/', include('django_kerberos.urls')),

And use the default authentication backend, by adding that to your `settings.py` file::

    AUTHENTICATION_BACKENDS = (
        'django_kerberos.backends.KerberosBackend',
    )

Settings
========

`KERBEROS_HOSTNAME`
-------------------

Hostname for retrieving the service key, the correspondig principal will be
`HTTP/{KERBEROS_HOSTNAME}@DEFAULT_REAML`, default is `None`. If `None` the hostname
from the request will be used.

`KERBEROS_BACKEND_CREATE`
-------------------------

Whether to create user if no existing model can be found, default is `False`.

`KERBEROS_BACKEND_ADMIN_REGEXP`
-------------------------------

A regular expression that the principal must match to get superuser privileges,
default is `None`. A classic example could be `r'^.*/admin$'`.

`KERBEROS_SERVICE_PRINCIPAL`
-----------------------------------

The service principal to use when checking a password against the
KDC, you don't need the secret key for this principal, it should
just exist inside the Kerberos database as the check is done by
trying to get ticket for this service. Default is
None. It's used only by the pseudo password haser
and the login/password authentication backend.

`KERBEROS_KEEP_PASSWORD`
------------------------

Does the KerbersoPasswordBackend store a hash of the
checked password inside the user model each time a
user log in. Default is False. It allows your
website to provide a backup authentication if
Kerberos is failing or if you ever need to detach
from the realm.

Custom backend
==============

A custom authentication backend can be used, in this case the signature of the
authenticate method must be::

    class CustomKerberosBackend(object):
        def authenticate(self, principal=None):
            pass

Sample application
==================

First you need to install django-kerberos into your environment like that::

    python setup.py install

If you want to try the sample application you must add this line to your `/etc/hosts` file, absolutely at the beginning::

    127.0.0.1 test.example.com

Then you must connect to your Kerberos administration server and add the
principal HTTP/test.example.com and export its key in a keytab file::

    $ kadmin -p myuser/admin
    kadmin: addprinc -randkey HTTP/test.example.com
    kadmin: ktadd -k /tmp/keytab HTTP/test.example.com

Finally you can run the sample::

    cd sample; KRB5_KTNAME=FILE:/tmp/keytab python ./manage.py runserver

Now you should be able to login on http://test.example.com:8000/

The sample project is configured so that all principal ending with `/admin` get
the staff and superuser flags. You can change that by editing the key
`KERBEROS_BACKEND_ADMIN_REGEXP` in `sample/sample/settings.py`.

.. caution::
   Only use A pointers for your domain name or if your domain name is a CNAME alias then create the HTTP principal for the target domain.

   Web browsers implementing the SPNEGO HTTP authenticiation protocol
   canonicalize domain names by always resolving to a DNS A record before
   building the corresponding principal. So if you have the following zone::

      test.example.com CNAME a.example.com
      a.example.com A a.b.c.d

   and if you connect to https://test.example.com then the browser is gonna try
   to get a ticket for the HTTP/a.examepl.com service principal not for
   HTTP/test.example.com.

Pseudo hasher
=============

A pseudo hasher whose import path is `django_kerberos.hashers.KerberosHasher`
provide a mean to associate a Django user model to a Kerberos identity.

The content of the password field must be `kerberos$<principal name>`.

To create an user for a principal you can do::

   User.objects.create(username=new_username, password='kerberos$' + principal)

Login/Password backend
======================

If your users does not have their browser configured
for SPNEGO HTTP authentication you can also provide
a classic login/password form which check passwords
using Kerberos.

Autologin
=========

A template include is provided to implement autologin. It calls the Kerberos
login view using AJAX. AJAX support in the login view makes the view return a
JSON document containing a boolean value indicating if login was sucessfull.
If login is succesfull the current view is reloaded.

To use this template just add the following code to any of your templates::

   {% include "django_kerberos/autologin.html" %}

After a succesfull login a cookie is created which prevent autologin for the
next 15 minutes, to permit login using other methods after an immediate logout.

The template show an HTML div having the id "kerberos-autologin" and containing
the text "Autologin..." so that you can add CSS styling to it.

The javascript implementation of autologin is a script named
"js/autlogin.html", it can be reused to implement autologin for other
proctocols. Its only requirement is to have a view which return 'true' if a
login is successfull on an HTTP GET request. The script provide a javascript
function whose signature is::

     autologin(url, callback[. timeout])

url is the URL of the login view, callback is a javascript function which will
receive true or false depending on the login success and timeout is the number
of seconds after a succesfull login during which autologin is disabled, default
is 15 minutes.
