LDAP/AD federation

What is it:

LDAP/AD Federation is the process of integrating enterprise directory services — such as Lightweight Directory Access Protocol (LDAP) directories or Microsoft Active Directory (AD) — with external applications or Identity Providers (IdPs) to enable secure and seamless authentication without duplicating user data. LDAP is a protocol standard for querying and modifying directory services over TCP/IP, while AD is a proprietary Microsoft directory service that implements LDAP and adds features like Kerberos authentication, group policy, and trust relationships. Federation abstracts the authentication process, allowing external systems (e.g., cloud applications, SaaS platforms, or identity brokers like Ping, ForgeRock, or Keycloak) to defer to internal LDAP/AD sources for credential validation.

Why it matters:

Federation with LDAP/AD is essential in modern identity architectures, especially for hybrid and enterprise-grade environments. It enables organizations to:

• Maintain a single source of truth for identities, avoiding data silos or redundancy.

• Provide Single Sign-On (SSO) across cloud and on-prem applications.

• Reduce password fatigue and improve user experience by centralizing credentials.

• Strengthen security with centralized policy enforcement (e.g., password policies, group memberships, access controls).

• Achieve regulatory compliance (e.g., PCI DSS, ISO 27001) through consistent identity governance and auditability.

How it works:

LDAP/AD Federation is typically implemented through a federation gateway or Identity Provider that mediates between external applications and internal directory services. Here's how it generally works:

1. A user initiates login to a federated application (e.g., Salesforce, ServiceNow, or a custom portal).

2. The application redirects the user to an IdP or gateway that supports protocols like SAML 2.0, OAuth2, or OpenID Connect.

3. The gateway authenticates the user against LDAP/AD using bind operations or Kerberos, depending on configuration.

4. Once authenticated, the IdP issues a token or assertion (e.g., SAML token or OIDC ID token) back to the application, granting access.

5. Attributes (e.g., email, groups, roles) can be mapped from LDAP/AD and passed as claims to enable authorization decisions downstream.

Advanced federation setups may also involve:

• Just-in-Time provisioning: Where users are dynamically created in the target system during login.

• Attribute transformation rules: For modifying LDAP attribute formats before token issuance.

• Integration with MFA systems: To enforce adaptive authentication beyond username/password.

• Trust relationships: Between forest domains or across multiple AD forests using ADFS or third-party brokers.