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A Django Central Authentication Service server implementing the CAS Protocol 3.0 Specification

Project description

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CAS Server is a Django application implementing the CAS Protocol 3.0 Specification.

By default, the authentication process use django internal users but you can easily use any sources (see auth classes in the file)


  • Support CAS version 1.0, 2.0, 3.0

  • Support Single Sign Out

  • Configuration of services via the django Admin application

  • Fine control on which user’s attributes are passed to which service

  • Possibility to rename/rewrite attributes per service

  • Possibility to require some attribute values per service

  • Federated mode between multiple CAS

  • Supports Django 1.7, 1.8 and 1.9

  • Supports Python 2.7, 3.x


django-cas-server depends on the following python packages:

  • Django >= 1.7 < 1.10

  • requests >= 2.4

  • requests_futures >= 0.9.5

  • lxml >= 3.4

  • six >= 1


The recommended installation mode is to use a virtualenv with --system-site-packages

  1. Make sure that python virtualenv is installed

  2. Install python packages available via the system package manager:

    On debian like systems:

    $ sudo apt-get install python-django python-requests python-six python-lxml python-requests-futures

    On debian jessie, you can use the version of python-django available in the backports.

    On centos like systems:

    $ sudo yum install python-django python-requests python-six python-lxml
  3. Create a virtualenv:

    $ virtualenv --system-site-packages cas_venv
    Running virtualenv with interpreter /var/www/html/cas-server/bin/python2
    Using real prefix '/usr'
    New python executable in cas/bin/python2
    Also creating executable in cas/bin/python
    Installing setuptools, pip...done.
    $ cd cas_venv/; . bin/activate
  4. Create a django project:

    $ django-admin startproject cas_project
    $ cd cas_project
  5. Install django-cas-server. To use the last published release, run:

    $ pip install django-cas-server

    Alternatively if you want to use the version of the git repository, you can clone it:

    $ git clone
    $ cd django-cas-server
    $ pip install -r requirements.txt

    Then, either run make install to create a python package using the sources of the repository and install it with pip, or place the cas_server directory into your PYTHONPATH (for instance by symlinking cas_server to the root of your django project).

  6. Open cas_project/ in you favourite editor and follow the quick start section.

Quick start

  1. Add “cas_server” to your INSTALLED_APPS setting like this:


    For internationalization support, add “django.middleware.locale.LocaleMiddleware” to your MIDDLEWARE_CLASSES setting like this:

  2. Include the cas_server URLconf in your project like this:

    from django.conf.urls import url, include
    urlpatterns = [
        url(r'^cas/', include('cas_server.urls', namespace="cas_server")),
  3. Run python migrate to create the cas_server models.

  4. You should add some management commands to a crontab: clearsessions, cas_clean_tickets and cas_clean_sessions.

    • clearsessions: please see Clearing the session store.

    • cas_clean_tickets: old tickets and timed-out tickets do not get purge from the database automatically. They are just marked as invalid. cas_clean_tickets is a clean-up management command for this purpose. It send SingleLogOut request to services with timed out tickets and delete them.

    • cas_clean_sessions: Logout and purge users (sending SLO requests) that are inactive since more than SESSION_COOKIE_AGE. The default value for is 1209600 seconds (2 weeks). You probably should reduce it to something like 86400 seconds (1 day).

    You could for example do as bellow :

    0   0  * * * cas-user /path/to/project/ clearsessions
    */5 *  * * * cas-user /path/to/project/ cas_clean_tickets
    5   0  * * * cas-user /path/to/project/ cas_clean_sessions
  5. Run python createsuperuser to create an administrator user.

  6. Start the development server and visit to add a first service allowed to authenticate user against the CAS (you’ll need the Admin app enabled). See the Service Patterns section bellow.

  7. Visit to login with your django users.


All settings are optional. Add them to to customize django-cas-server:

Template settings

  • CAS_LOGO_URL: URL to the logo showed in the up left corner on the default templates. Set it to False to disable it.

  • CAS_COMPONENT_URLS: URLs to css and javascript external components. It is a dictionnary and it must have the five following keys: "bootstrap3_css", "bootstrap3_js", "html5shiv", "respond", "jquery". The default is:

        "bootstrap3_css": "//",
        "bootstrap3_js": "//",
        "html5shiv": "//",
        "respond": "//",
        "jquery": "//",
  • CAS_LOGIN_TEMPLATE: Path to the template showed on /login then the user is not autenticated. The default is "cas_server/login.html".

  • CAS_WARN_TEMPLATE: Path to the template showed on /login?service=... then the user is authenticated and has asked to be warned before being connected to a service. The default is "cas_server/warn.html".

  • CAS_LOGGED_TEMPLATE: Path to the template showed on /login then to user is authenticated. The default is "cas_server/logged.html".

  • CAS_LOGOUT_TEMPLATE: Path to the template showed on /logout then to user is being disconnected. The default is "cas_server/logout.html"

  • CAS_REDIRECT_TO_LOGIN_AFTER_LOGOUT: Should we redirect users to /login after they logged out instead of displaying CAS_LOGOUT_TEMPLATE. The default is False.

Authentication settings

  • CAS_AUTH_CLASS: A dotted path to a class or a class implementing cas_server.auth.AuthUser. The default is "cas_server.auth.DjangoAuthUser"

  • SESSION_COOKIE_AGE: This is a django settings. Here, it control the delay in seconds after which inactive users are logged out. The default is 1209600 (2 weeks). You probably should reduce it to something like 86400 seconds (1 day).

  • CAS_PROXY_CA_CERTIFICATE_PATH: Path to certificate authorities file. Usually on linux the local CAs are in /etc/ssl/certs/ca-certificates.crt. The default is True which tell requests to use its internal certificat authorities. Settings it to False should disable all x509 certificates validation and MUST not be done in production. x509 certificate validation is perform upon PGT issuance.

  • CAS_SLO_MAX_PARALLEL_REQUESTS: Maximum number of parallel single log out requests send. If more requests need to be send, there are queued. The default is 10.

  • CAS_SLO_TIMEOUT: Timeout for a single SLO request in seconds. The default is 5.

Federation settings

  • CAS_FEDERATE: A boolean for activating the federated mode (see the federate section below). The default is False.

  • CAS_FEDERATE_REMEMBER_TIMEOUT: Time after witch the cookie use for “remember my identity provider” expire. The default is 604800, one week. The cookie is called _remember_provider.

Tickets validity settings

  • CAS_TICKET_VALIDITY: Number of seconds the service tickets and proxy tickets are valid. This is the maximal time between ticket issuance by the CAS and ticket validation by an application. The default is 60.

  • CAS_PGT_VALIDITY: Number of seconds the proxy granting tickets are valid. The default is 3600 (1 hour).

  • CAS_TICKET_TIMEOUT: Number of seconds a ticket is kept in the database before sending Single Log Out request and being cleared. The default is 86400 (24 hours).

Tickets miscellaneous settings

  • CAS_TICKET_LEN: Default ticket length. All CAS implementation MUST support ST and PT up to 32 chars, PGT and PGTIOU up to 64 chars and it is RECOMMENDED that all tickets up to 256 chars are supports. Here the default is 64.

  • CAS_LT_LEN: Length of the login tickets. Login tickets are only processed by django-cas-server thus there is no length restriction on it. The default is CAS_TICKET_LEN.

  • CAS_ST_LEN: Length of the service tickets. The default is CAS_TICKET_LEN. You may need to lower is to 32 if you use some old clients.

  • CAS_PT_LEN: Length of the proxy tickets. The default is CAS_TICKET_LEN. This length should be the same as CAS_ST_LEN. You may need to lower is to 32 if you use some old clients.

  • CAS_PGT_LEN: Length of the proxy granting tickets. The default is CAS_TICKET_LEN.

  • CAS_PGTIOU_LEN: Length of the proxy granting tickets IOU. The default is CAS_TICKET_LEN.

  • CAS_LOGIN_TICKET_PREFIX: Prefix of login tickets. The default is "LT".

  • CAS_SERVICE_TICKET_PREFIX: Prefix of service tickets. The default is "ST". The CAS specification mandate that service tickets MUST begin with the characters ST so you should not change this.

  • CAS_PROXY_TICKET_PREFIX: Prefix of proxy ticket. The default is "PT".

  • CAS_PROXY_GRANTING_TICKET_PREFIX: Prefix of proxy granting ticket. The default is "PGT".

  • CAS_PROXY_GRANTING_TICKET_IOU_PREFIX: Prefix of proxy granting ticket IOU. The default is "PGTIOU".

Mysql backend settings

Only usefull if you are using the mysql authentication backend:

  • CAS_SQL_HOST: Host for the SQL server. The default is "localhost".

  • CAS_SQL_USERNAME: Username for connecting to the SQL server.

  • CAS_SQL_PASSWORD: Password for connecting to the SQL server.

  • CAS_SQL_DBNAME: Database name.

  • CAS_SQL_DBCHARSET: Database charset. The default is "utf8"

  • CAS_SQL_USER_QUERY: The query performed upon user authentication. The username must be in field username, the password in password, additional fields are used as the user attributes. The default is "SELECT user AS username, pass AS password, users.* FROM users WHERE user = %s"

  • CAS_SQL_PASSWORD_CHECK: The method used to check the user password. Must be one of the following:

    • "crypt" (see <>), the password in the database should begin this $

    • "ldap" (see the password in the database must begin with one of {MD5}, {SMD5}, {SHA}, {SSHA}, {SHA256}, {SSHA256}, {SHA384}, {SSHA384}, {SHA512}, {SSHA512}, {CRYPT}.

    • "hex_HASH_NAME" with HASH_NAME in md5, sha1, sha224, sha256, sha384, sha512. The hashed password in the database is compare to the hexadecimal digest of the clear password hashed with the corresponding algorithm.

    • "plain", the password in the database must be in clear.

    The default is "crypt".

Test backend settings

Only usefull if you are using the test authentication backend:

  • CAS_TEST_USER: Username of the test user. The default is "test".

  • CAS_TEST_PASSWORD: Password of the test user. The default is "test".

  • CAS_TEST_ATTRIBUTES: Attributes of the test user. The default is {'nom': 'Nymous', 'prenom': 'Ano', 'email': '', 'alias': ['demo1', 'demo2']}.

Authentication backend

django-cas-server comes with some authentication backends:

  • dummy backend cas_server.auth.DummyAuthUser: all authentication attempt fails.

  • test backend cas_server.auth.TestAuthUser: username, password and returned attributes for the user are defined by the CAS_TEST_* settings.

  • django backend cas_server.auth.DjangoAuthUser: Users are authenticated against django users system. This is the default backend. The returned attributes are the fields available on the user model.

  • mysql backend cas_server.auth.MysqlAuthUser: see the ‘Mysql backend settings’ section. The returned attributes are those return by sql query CAS_SQL_USER_QUERY.

  • federated backend cas_server.auth.CASFederateAuth: It is automatically used then CAS_FEDERATE is True. You should not set it manually without setting CAS_FEDERATE to True.


django-cas-server logs most of its actions. To enable login, you must set the LOGGING ( variable in

Users successful actions (login, logout) are logged with the level INFO, failures are logged with the level WARNING and user attributes transmitted to a service are logged with the level DEBUG.

For example to log to syslog you can use :

    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'cas_syslog': {
            'format': 'cas: %(levelname)s %(message)s'
    'handlers': {
        'cas_syslog': {
            'level': 'INFO',
            'class': 'logging.handlers.SysLogHandler',
            'address': '/dev/log',
            'formatter': 'cas_syslog',
    'loggers': {
        'cas_server': {
            'handlers': ['cas_syslog'],
            'level': 'INFO',
            'propagate': True,

Or to log to a file:

    'version': 1,
    'disable_existing_loggers': False,
    'formatters': {
        'cas_file': {
            'format': '%(asctime)s %(levelname)s %(message)s'
    'handlers': {
        'cas_file': {
            'level': 'INFO',
            'class': 'logging.FileHandler',
            'filename': '/tmp/cas_server.log',
            'formatter': 'cas_file',
    'loggers': {
        'cas_server': {
            'handlers': ['cas_file'],
            'level': 'INFO',
            'propagate': True,

Service Patterns

In a CAS context, Service refers to the application the client is trying to access. By extension we use service for the URL of such an application.

By default, django-cas-server do not allow any service to use the CAS to authenticate users. In order to allow services, you need to connect to the django admin interface using a django superuser, and add a first service pattern.

A service pattern comes with 9 fields:

  • Position: an integer used to change the order in which services are matched against service patterns.

  • Name: the name of the service pattern. It will be displayed to the users asking for a ticket for a service matching this service pattern on the login page.

  • Pattern: a regular expression used to match services.

  • User field: the user attribute to use as username for services matching this service pattern. Leave it empty to use the login name.

  • Restrict username: if checked, only login name defined below are allowed to get tickets for services matching this service pattern.

  • Proxy: if checked, allow the creation of Proxy Ticket for services matching this service pattern. Otherwise, only Service Ticket will be created.

  • Proxy callback: if checked, services matching this service pattern are allowed to retrieve Proxy Granting Ticket. A service with a Proxy Granting Ticket can get Proxy Ticket for other services. Hence you must only check this for trusted services that need it. (For instance, a webmail needs Proxy Ticket to authenticate himself as the user to the imap server).

  • Single log out: Check it to send Single Log Out requests to authenticated services matching this service pattern. SLO requests are send to all services the user is authenticated to then the user disconnect.

  • Single log out callback: The http(s) URL to POST the SLO requests. If empty, the service URL is used. This field is useful to allow non http services (imap, smtp, ftp) to handle SLO requests.

A service pattern has 4 associated models:

  • Usernames: a list of username associated with the Restrict username field

  • Replace attribut names: a list of user attributes to send to the service. Choose the name used for sending the attribute by setting Remplacement or leave it empty to leave it unchanged.

  • Replace attribut values: a list of sent user attributes for which value needs to be tweak. Replace the attribute value by the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by replace. In replace backslash escapes are processed. Matched groups are captures by 1, 2, etc.

  • Filter attribut values: a list of user attributes for which value needs to match a regular expression. For instance, service A may need an email address, and you only want user with an email address to connect to it. To do so, put email in Attribute and .* in pattern.

Then a user ask a ticket for a service, the service URL is compare against each service patterns sorted by position. The first service pattern that matches the service URL is chosen. Hence, you should give low position to very specific patterns like ^https://www\.example\.com(/.*)?$ and higher position to generic patterns like ^https://.*. So the service URL will use the service pattern for ^https://www\.example\.com(/.*)?$ and not the one for ^https://.*.

Federation mode

django-cas-server comes with a federation mode. Then CAS_FEDERATE is True, user are invited to choose an identity provider on the login page, then, they are redirected to the provider CAS to authenticate. This provider transmit to django-cas-server the user username and attributes. The user is now logged in on django-cas-server and can use services using django-cas-server as CAS.

The list of allowed identity providers is defined using the django admin application. With the development server started, visit to add identity providers.

An identity provider comes with 5 fields:

  • Position: an integer used to tweak the order in which identity providers are displayed on the login page. Identity providers are sorted using position first, then, on equal position, using verbose name and then, on equal verbose name, using suffix.

  • Suffix: the suffix that will be append to the username returned by the identity provider. It must be unique.

  • Server url: the URL to the identity provider CAS. For instance, if you are using to authenticate on the CAS, the server url is

  • CAS protocol version: the version of the CAS protocol to use to contact the identity provider. The default is version 3.

  • Verbose name: the name used on the login page to display the identity provider.

  • Display: a boolean controlling the display of the identity provider on the login page. Beware that this do not disable the identity provider, it just hide it on the login page. User will always be able to log in using this provider by fetching /federate/provider_suffix.

In federation mode, django-cas-server build user’s username as follow: provider_returned_username@provider_suffix. Choose the provider returned username for django-cas-server and the provider suffix in order to make sense, as this built username is likely to be displayed to end users in applications.

Then using federate mode, you should add one command to a daily crontab: cas_clean_federate. This command clean the local cache of federated user from old unused users.

You could for example do as bellow :

10   0  * * * cas-user /path/to/project/ cas_clean_federate

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