This document describes how to make use of external authentication sources (where the Web server sets the
REMOTE_USER environment variable) in your Django applications. This type of authentication solution is typically seen on intranet sites, with single sign-on solutions such as IIS and Integrated Windows Authentication or Apache and mod_authnz_ldap, CAS, Cosign, WebAuth, mod_auth_sspi, etc.
When the Web server takes care of authentication it typically sets the
REMOTE_USER environment variable for use in the underlying application. In Django,
REMOTE_USER is made available in the request.META attribute. Django can be configured to make use of the
REMOTE_USER value using the
PersistentRemoteUserMiddleware, and RemoteUserBackend classes found in django.contrib.auth.
First, you must add the django.contrib.auth.middleware.RemoteUserMiddleware to the MIDDLEWARE setting after the django.contrib.auth.middleware.AuthenticationMiddleware:
MIDDLEWARE = [ '...', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.auth.middleware.RemoteUserMiddleware', '...', ]
AUTHENTICATION_BACKENDS = [ 'django.contrib.auth.backends.RemoteUserBackend', ]
With this setup,
RemoteUserMiddleware will detect the username in
request.META['REMOTE_USER'] and will authenticate and auto-login that user using the RemoteUserBackend.
Be aware that this particular setup disables authentication with the default
ModelBackend. This means that if the
REMOTE_USER value is not set then the user is unable to log in, even using Django’s admin interface. Adding
'django.contrib.auth.backends.ModelBackend' to the
AUTHENTICATION_BACKENDS list will use
ModelBackend as a fallback if
REMOTE_USER is absent, which will solve these issues.
Django’s user management, such as the views in
contrib.admin and the createsuperuser management command, doesn’t integrate with remote users. These interfaces work with users stored in the database regardless of
RemoteUserBackend inherits from
ModelBackend, you will still have all of the same permissions checking that is implemented in
If your authentication mechanism uses a custom HTTP header and not
REMOTE_USER, you can subclass
RemoteUserMiddleware and set the
header attribute to the desired
request.META key. For example:
from django.contrib.auth.middleware import RemoteUserMiddleware class CustomHeaderMiddleware(RemoteUserMiddleware): header = 'HTTP_AUTHUSER'
Be very careful if using a
RemoteUserMiddleware subclass with a custom HTTP header. You must be sure that your front-end web server always sets or strips that header based on the appropriate authentication checks, never permitting an end-user to submit a fake (or “spoofed”) header value. Since the HTTP headers
X-Auth_User (for example) both normalize to the
HTTP_X_AUTH_USER key in
request.META, you must also check that your web server doesn’t allow a spoofed header using underscores in place of dashes.
This warning doesn’t apply to
RemoteUserMiddleware in its default configuration with
header = 'REMOTE_USER', since a key that doesn’t start with
request.META can only be set by your WSGI server, not directly from an HTTP request header.
If you need more control, you can create your own authentication backend that inherits from RemoteUserBackend and override one or more of its attributes and methods.
RemoteUserMiddleware authentication middleware assumes that the HTTP request header
REMOTE_USER is present with all authenticated requests. That might be expected and practical when Basic HTTP Auth with
htpasswd or similar mechanisms are used, but with Negotiate (GSSAPI/Kerberos) or other resource intensive authentication methods, the authentication in the front-end HTTP server is usually only set up for one or a few login URLs, and after successful authentication, the application is supposed to maintain the authenticated session itself.
PersistentRemoteUserMiddleware provides support for this use case. It will maintain the authenticated session until explicit logout by the user. The class can be used as a drop-in replacement of RemoteUserMiddleware in the documentation above.