Authenticating against an LDAP server

Symfony provides different means to work with an LDAP server.

The Security component offers:

The ldap user provider , using the LdapUserProvider class. Like all other user providers, it can be used with any authentication provider.

The form_login_ldap authentication provider, for authenticating against an LDAP server using a login form. Like all other authentication providers, it can be used with any user provider.

The http_basic_ldap authentication provider, for authenticating against an LDAP server using HTTP Basic. Like all other authentication providers, it can be used with any user provider.

This means that the following scenarios will work:

Checking a user's password and fetching user information against an LDAP server. This can be done using both the LDAP user provider and either the LDAP form login or LDAP HTTP Basic authentication providers.

Checking a user's password against an LDAP server while fetching user information from another source (database using FOSUserBundle, for example).

Loading user information from an LDAP server, while using another authentication strategy (token-based pre-authentication, for example).

Installation

In applications using Symfony Flex , run this command to install the Ldap component before using it:

$ composer require symfony/ldap

Ldap Configuration Reference

See Security Configuration Reference (SecurityBundle) for the full LDAP configuration reference ( form_login_ldap , http_basic_ldap , ldap ). Some of the more interesting options are explained below.

Configuring the LDAP client

All mechanisms actually need an LDAP client previously configured. The providers are configured to use a default service named ldap , but you can override this setting in the security component's configuration.

An LDAP client can be configured using the built-in LDAP PHP extension with the following service definition:

services: Symfony\Component\Ldap\Ldap: arguments: ['@Symfony\Component\Ldap\Adapter\ExtLdap\Adapter'] tags: - ldap Symfony\Component\Ldap\Adapter\ExtLdap\Adapter: arguments: - host: my-server port: 389 encryption: tls options: protocol_version: 3 referrals: false

<!-- config/services.xml -->
<?xml version="1.0" encoding="UTF-8" ?>
<container xmlns="http://symfony.com/schema/dic/services"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://symfony.com/schema/dic/services https://symfony.com/schema/dic/services/services-1.0.xsd">
    <services>
        <service id="Symfony\Component\Ldap\Ldap">
            <argument type="service" id="Symfony\Component\Ldap\Adapter\ExtLdap\Adapter"/>
            <tag name="ldap"/>
        </service>
        <service id="Symfony\Component\Ldap\Adapter\ExtLdap\Adapter">
            <argument type="collection">
                <argument key="host">my-server</argument>
                <argument key="port">389</argument>
                <argument key="encryption">tls</argument>
                <argument key="options" type="collection">
                    <argument key="protocol_version">3</argument>
                    <argument key="referrals">false</argument>
                </argument>
            </argument>
        </service>
    </services>
</container>

// config/services.php
use Symfony\Component\Ldap\Adapter\ExtLdap\Adapter;
use Symfony\Component\Ldap\Ldap;
$container->register(Ldap::class)
    ->addArgument(new Reference(Adapter::class))
    ->tag('ldap');
$container
    ->register(Adapter::class)
    ->setArguments([
        'host' => 'my-server',
        'port' => 389,
        'encryption' => 'tls',
        'options' => [
            'protocol_version' => 3,
            'referrals' => false
Fetching Users Using the LDAP User Provider
If you want to fetch user information from an LDAP server, you may want to
use the ldap user provider.
                service: Symfony\Component\Ldap\Ldap
                base_dn: dc=example,dc=com
                search_dn: "cn=read-only-admin,dc=example,dc=com"
                search_password: password
                default_roles: ROLE_USER
                uid_key: uid
                extra_fields: ['email']

<!-- config/packages/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
        https://symfony.com/schema/dic/services/services-1.0.xsd
        http://symfony.com/schema/dic/security
        https://symfony.com/schema/dic/security/security-1.0.xsd">
    <config>
        <provider name="my_ldap">
            <ldap service="Symfony\Component\Ldap\Ldap"
                base-dn="dc=example,dc=com"
                search-dn="cn=read-only-admin,dc=example,dc=com"
                search-password="password"
                default-roles="ROLE_USER"
                uid-key="uid"/>
        </provider>
    </config>
</srv:container>

// config/packages/security.php
use Symfony\Component\Ldap\Ldap;
use Symfony\Config\SecurityConfig;
return static function (SecurityConfig $security): void {
    $security->provider('ldap_users')
        ->ldap()
            ->service(Ldap::class)
            ->baseDn('dc=example,dc=com')
            ->searchDn('cn=read-only-admin,dc=example,dc=com')
            ->searchPassword('password')
            ->defaultRoles(['ROLE_USER'])
            ->uidKey('uid')
            ->extraFields(['email'])
                Caution
    
The Security component escapes provided input data when the LDAP user
provider is used. However, the LDAP component itself does not provide
any escaping yet. Thus, it's your responsibility to prevent LDAP injection
attacks when using the component directly.
                Caution
    
The user configured above in the user provider is only used to retrieve
data. It's a static user defined by its username and password (for improved
security, define the password as an environment variable).
If your LDAP server allows retrieval of information anonymously, you can
set the search_dn and search_password options to null.
The ldap user provider supports many different configuration options:
service
type: string default: ldap
This is the name of your configured LDAP client. You can freely choose the
name, but it must be unique in your application and it cannot start with a
number or contain white spaces.
base_dn
type: string default: null
This is the base DN for the directory
search_dn
type: string default: null
This is your read-only user's DN, which will be used to authenticate
against the LDAP server to fetch the user's information.
search_password
type: string default: null
This is your read-only user's password, which will be used to authenticate
against the LDAP server to fetch the user's information.
default_roles
type: array default: []
This is the default role you wish to give to a user fetched from the LDAP
server. If you do not configure this key, your users won't have any roles,
and will not be considered as authenticated fully.
uid_key
type: string default: null
This is the entry's key to use as its UID. Depends on your LDAP server
implementation. Commonly used values are:
    
sAMAccountName (default)
userPrincipalName
If you pass null as the value of this option, the default UID key is used
sAMAccountName.
extra_fields
type: array default: null
Defines the custom fields to pull from the LDAP server. If any field does not
exist, an \InvalidArgumentException will be thrown.
filter
type: string default: null
This key lets you configure which LDAP query will be used. The {uid_key}
string will be replaced by the value of the uid_key configuration value
(by default, sAMAccountName), and the {user_identifier} string will be
replaced by the user identified you are trying to load.
For example, with a uid_key of uid, and if you are trying to
load the user fabpot, the final string will be: (uid=fabpot).
If you pass null as the value of this option, the default filter is used
({uid_key}={user_identifier}).
To prevent LDAP injection, the username will be escaped.
The syntax for the filter key is defined by RFC4515.
Authenticating against an LDAP server
Authenticating against an LDAP server can be done using either the form
login or the HTTP Basic authentication providers.
They are configured exactly as their non-LDAP counterparts, with the
addition of two configuration keys and one optional key:
service
type: string default: ldap
This is the name of your configured LDAP client. You can freely choose the
name, but it must be unique in your application and it cannot start with a
number or contain white spaces.
dn_string
type: string default: {user_identifier}
This key defines the form of the string used to compose the
DN of the user, from the username. The {user_identifier} string is
replaced by the actual username of the person trying to authenticate.
For example, if your users have DN strings in the form
uid=einstein,dc=example,dc=com, then the dn_string will be
uid={user_identifier},dc=example,dc=com.
query_string
type: string default: null
This (optional) key makes the user provider search for a user and then use the
found DN for the bind process. This is useful when using multiple LDAP user
providers with different base_dn. The value of this option must be a valid
search string (e.g. uid="{user_identifier}"). The placeholder value will be
replaced by the actual user identifier.
When this option is used, query_string will search in the DN specified by
dn_string and the DN resulted of the query_string will be used to
authenticate the user with their password. Following the previous example, if
your users have the following two DN: dc=companyA,dc=example,dc=com and
dc=companyB,dc=example,dc=com, then dn_string should be
dc=example,dc=com.
Bear in mind that usernames must be unique across both DN, as the authentication
provider won't be able to select the correct user for the bind process if more
than one is found.
Examples are provided below, for both form_login_ldap and
http_basic_ldap.
Configuration example for form login
        
<!-- config/packages/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
        https://symfony.com/schema/dic/services/services-1.0.xsd
        http://symfony.com/schema/dic/security
        https://symfony.com/schema/dic/security/security-1.0.xsd">
    <config>
        <firewall name="main">
            <form-login-ldap service="Symfony\Component\Ldap\Ldap"
                dn-string="uid={user_identifier},dc=example,dc=com"/>
        </firewall>
    </config>
</srv:container>
        
// config/packages/security.php
use Symfony\Component\Ldap\Ldap;
use Symfony\Config\SecurityConfig;
return static function (SecurityConfig $security): void {
    $security->firewall('main')
        ->formLoginLdap()
            ->service(Ldap::class)
            ->dnString('uid={user_identifier},dc=example,dc=com')
        
<!-- config/packages/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
        https://symfony.com/schema/dic/services/services-1.0.xsd
        http://symfony.com/schema/dic/security
        https://symfony.com/schema/dic/security/security-1.0.xsd">
    <config>
        <!-- ... -->
        <firewall name="main" stateless="true">
            <http-basic-ldap service="Symfony\Component\Ldap\Ldap"
                dn-string="uid={user_identifier},dc=example,dc=com"/>
        </firewall>
    </config>
</srv:container>
        
// config/packages/security.php
use Symfony\Component\Ldap\Ldap;
use Symfony\Config\SecurityConfig;
return static function (SecurityConfig $security): void {
    $security->firewall('main')
        ->stateless(true)
        ->formLoginLdap()
            ->service(Ldap::class)
            ->dnString('uid={user_identifier},dc=example,dc=com')
                service: Symfony\Component\Ldap\Ldap
                dn_string: 'dc=example,dc=com'
                query_string: '(&(uid={user_identifier})(memberOf=cn=users,ou=Services,dc=example,dc=com))'
                search_dn: '...'
                search_password: 'the-raw-password'
        
<!-- config/packages/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
        https://symfony.com/schema/dic/services/services-1.0.xsd
        http://symfony.com/schema/dic/security
        https://symfony.com/schema/dic/security/security-1.0.xsd">
    <config>
        <firewall name="main">
            <!-- ... -->
            <form-login-ldap service="Symfony\Component\Ldap\Ldap"
                dn-string="dc=example,dc=com"
                query-string="(&amp;(uid={user_identifier})(memberOf=cn=users,ou=Services,dc=example,dc=com))"
                search-dn="..."
                search-password="the-raw-password"/>
        </firewall>
    </config>
</srv:container>
        
// config/packages/security.php
use Symfony\Component\Ldap\Ldap;
use Symfony\Config\SecurityConfig;
return static function (SecurityConfig $security): void {
    $security->firewall('main')
        ->stateless(true)
        ->formLoginLdap()
            ->service(Ldap::class)
            ->dnString('dc=example,dc=com')
            ->queryString('(&(uid={user_identifier})(memberOf=cn=users,ou=Services,dc=example,dc=com))')
            ->searchDn('...')
            ->searchPassword('the-raw-password')
                                
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