Using pre Authenticated Security Firewalls

Using pre Authenticated Security Firewalls

A lot of authentication modules are already provided by some web servers, including Apache. These modules generally set some environment variables that can be used to determine which user is accessing your application. Out of the box, Symfony supports most authentication mechanisms. These requests are called pre authenticated requests because the user is already authenticated when reaching your application.

Caution

User impersonation is not compatible with pre-authenticated firewalls. The reason is that impersonation requires the authentication state to be maintained server-side, but pre-authenticated information (SSL_CLIENT_S_DN_Email, REMOTE_USER or other) is sent in each request.

X.509 Client Certificate Authentication

When using client certificates, your webserver is doing all the authentication process itself. With Apache, for example, you would use the SSLVerifyClient Require directive.

Enable the x509 authentication for a particular firewall in the security configuration:

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    # app/config/security.yml
    security:
        # ...
    
        firewalls:
            secured_area:
                pattern: ^/
                x509:
                    provider: your_user_provider
    
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    <!-- app/config/security.xml -->
    <?xml version="1.0" encoding="UTF-8"?>
    <srv:container xmlns="http://symfony.com/schema/dic/security"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:srv="http://symfony.com/schema/dic/services"
        xsi:schemaLocation="http://symfony.com/schema/dic/services
            http://symfony.com/schema/dic/services/services-1.0.xsd">
    
        <config>
            <!-- ... -->
    
            <firewall name="secured_area" pattern="^/">
                <x509 provider="your_user_provider" />
            </firewall>
        </config>
    </srv:container>
    
  • PHP
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    // app/config/security.php
    $container->loadFromExtension('security', array(
        // ...
    
        'firewalls' => array(
            'secured_area' => array(
                'pattern' => '^/',
                'x509'    => array(
                    'provider' => 'your_user_provider',
                ),
            ),
        ),
    ));
    

By default, the firewall provides the SSL_CLIENT_S_DN_Email variable to the user provider, and sets the SSL_CLIENT_S_DN as credentials in the PreAuthenticatedToken. You can override these by setting the user and the credentials keys in the x509 firewall configuration respectively.

Note

An authentication provider will only inform the user provider of the username that made the request. You will need to create (or use) a "user provider" that is referenced by the provider configuration parameter (your_user_provider in the configuration example). This provider will turn the username into a User object of your choice. For more information on creating or configuring a user provider, see:

REMOTE_USER Based Authentication

A lot of authentication modules, like auth_kerb for Apache provide the username using the REMOTE_USER environment variable. This variable can be trusted by the application since the authentication happened before the request reached it.

To configure Symfony using the REMOTE_USER environment variable, simply enable the corresponding firewall in your security configuration:

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    # app/config/security.yml
    security:
        firewalls:
            secured_area:
                pattern: ^/
                remote_user:
                    provider: your_user_provider
    
  • XML
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    <!-- app/config/security.xml -->
    <?xml version="1.0" ?>
    <srv:container xmlns="http://symfony.com/schema/dic/security"
        xmlns:srv="http://symfony.com/schema/dic/services">
    
        <config>
            <firewall name="secured_area" pattern="^/">
                <remote-user provider="your_user_provider"/>
            </firewall>
        </config>
    </srv:container>
    
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    // app/config/security.php
    $container->loadFromExtension('security', array(
        'firewalls' => array(
            'secured_area' => array(
                'pattern'     => '^/',
                'remote_user' => array(
                    'provider' => 'your_user_provider',
                ),
            ),
        ),
    ));
    

The firewall will then provide the REMOTE_USER environment variable to your user provider. You can change the variable name used by setting the user key in the remote_user firewall configuration.

Note

Just like for X509 authentication, you will need to configure a "user provider". See the previous note for more information.

This work, including the code samples, is licensed under a Creative Commons BY-SA 3.0 license.