Active Directory Federation Services (AD FS) is a Microsoft identity and access management technology that allows for secure, single sign-on (SSO) access to applications across different security domains, both on-premises and in the cloud. AD FS enables users to log in once with their organization’s credentials and access various applications without the need to re-enter their credentials. It plays a pivotal role in providing authentication and access control for federated identity scenarios, especially with cloud services like Azure. Here’s a detailed explanation of the concept, including the workflow for connecting to Azure services and descriptions of token types and content:
Concept of AD FS:
AD FS uses a claims-based authentication model, where the focus is on exchanging security tokens. A security token is a package of data that contains claims (attributes or assertions about the user), the issuer’s signature, and information about the token’s lifespan. Here’s how AD FS works in a scenario where a user connects to Azure services:
Workflow for Connecting to Azure Services with AD FS:
- User Authentication: A user attempts to access an Azure service (e.g., Microsoft 365) or a federated application.
- Request for a Security Token: The Azure service or federated application requests a security token to verify the user’s identity. This request is usually initiated through a standardized protocol like Security Assertion Markup Language (SAML) or OpenID Connect.
- Security Token Issuance: The request is forwarded to the AD FS server. AD FS authenticates the user against the on-premises Active Directory (AD) and issues a security token.
- Security Token Delivery: The issued security token is sent back to the Azure service or federated application. This token is digitally signed by AD FS, ensuring its authenticity.
- Token Validation: The Azure service or federated application validates the received token. It checks the digital signature to ensure that the token was indeed issued by the trusted AD FS server.
- User Access: If the token is valid, the user is granted access to the Azure service or federated application without having to provide credentials again.
Token Types and Content:
In the context of AD FS and connecting to Azure services, the most common token types are SAML tokens and OAuth tokens. The content of these tokens may include:
- SAML Tokens:
- Claims: These are attributes about the user, such as username, email, group membership, or custom attributes.
- Issuer’s Signature: A digital signature from the AD FS server to ensure the authenticity and integrity of the token.
- Token Lifespan: Information about when the token was issued and when it expires.
- OAuth Tokens:
- Access Tokens: These tokens are used to grant access to specific Azure services or APIs. They include claims and are often short-lived.
- Refresh Tokens: These are used to obtain new access tokens without requiring the user to re-enter their credentials.
- ID Tokens: These tokens provide information about the user’s identity.
Working and Use Cases:
- Single Sign-On (SSO): One of the primary use cases for AD FS is to provide SSO for users accessing Azure services, Microsoft 365, or other federated applications.
- Hybrid Identity: AD FS is often used in hybrid identity scenarios where organizations maintain both on-premises and cloud-based resources. AD FS ensures a seamless identity and authentication experience.
- Security and Access Control: AD FS helps maintain security by controlling who can access Azure services and other applications, based on AD attributes and policies.
- Custom Authentication: Organizations can implement custom authentication flows with AD FS, such as multi-factor authentication (MFA), smart card authentication, and more.
AD FS plays a crucial role in extending an organization’s identity and authentication infrastructure to the cloud, offering a secure and seamless experience for users accessing Azure and federated applications.
Active Directory Federation Services (AD FS) is a component of Microsoft Windows Server that provides a single sign-on (SSO) solution for authenticating users and enabling secure access to applications across different security domains. It allows organizations to authenticate users with their on-premises credentials and enable SSO to cloud-based and on-premises applications. Here’s a detailed description of AD FS, including prerequisites, features, and a step-by-step guide on how to configure it, along with a server infrastructure environment description.
Prerequisites:
Before configuring AD FS, ensure you have the following prerequisites:
- Windows Server: You need a Windows Server running Windows Server 2012 R2 or later to install AD FS.
- Domain Controller: You must have a functional on-premises Active Directory domain controller.
- DNS: Ensure DNS is configured correctly in your network.
- SSL Certificate: Acquire a valid SSL certificate for the AD FS service name.
- Firewall Rules: Open the necessary ports (e.g., 80, 443) on your network’s firewall to allow incoming traffic to AD FS.
Features and Functions:
- Single Sign-On (SSO): AD FS provides SSO capabilities, enabling users to log in once and access multiple applications without the need to re-enter credentials.
- Claims-Based Authentication: AD FS uses claims-based authentication to pass user attributes (claims) between the identity provider (AD FS) and the relying party (application).
- Multi-Factor Authentication (MFA): AD FS supports MFA, enhancing security by requiring users to provide multiple forms of authentication.
- Federation with Cloud Services: AD FS enables federation with cloud services like Microsoft 365, Azure, and third-party SaaS applications.
- Home Realm Discovery: Allows users to select their identity provider when multiple identity providers are configured.
- Access Control Policies: AD FS provides access control policies to enforce authorization rules for access to applications.
- Token-Based Security: AD FS uses security tokens for authentication, ensuring secure communication between the identity provider and relying parties.
- Claim Transformation: You can transform claims between different claim types for compatibility with applications.
Step-by-Step Guide to Configure AD FS:
Below is a high-level step-by-step guide on how to configure AD FS:
Server Infrastructure Environment Description:
For the purpose of this guide, let’s assume the following server infrastructure environment:
- Active Directory Domain Controller: You have an on-premises Active Directory domain controller running Windows Server.
- Windows Server: You have a Windows Server 2012 R2 or later system that you want to configure as your AD FS server.
- DNS: Your DNS is properly configured in your network.
- SSL Certificate: You have acquired an SSL certificate for your AD FS service.
AD FS Configuration:
- Install AD FS Role:
- On your Windows Server, open Server Manager, add the AD FS role, and install the required components.
- AD FS Configuration Wizard:
- After installation, open the AD FS Configuration Wizard. Configure AD FS farm properties and specify the service name for your AD FS.
- SSL Certificate:
- Select the SSL certificate you acquired for AD FS during the configuration process.
- Federation with Cloud Services:
- If you want to enable federation with cloud services like Microsoft 365, configure trust relationships with the respective service.
- Access Control Policies:
- Define access control policies to enforce authorization rules for your applications.
- Testing:
- Test the AD FS configuration by attempting to log in to an application that uses AD FS for authentication.
Once configured, AD FS will provide secure authentication and SSO for your on-premises and cloud-based applications. Users can seamlessly access applications with their on-premises credentials.
