Many organizations adopting Amazon Web Services (AWS) want employees to access AWS using existing corporate credentials such as LDAP or Active Directory. This article explains how AWS identity federation enables secure, scalable access without creating long-lived IAM users or duplicate identities.
Enterprises frequently ask a critical question early in their cloud journey: Can teams use the same corporate credentials to access AWS? Organizations that already rely on LDAP or Active Directory want to reuse existing identities, centralize authentication, and maintain strong security controls.
This blog outlines a proven AWS architecture that separates authentication from authorization, uses IAM roles with temporary credentials, and aligns with AWS security best practices.
The Core Challenge: Authentication vs Authorization in AWS
AWS Identity and Access Management (IAM) controls authorization for AWS resources, but it does not authenticate users against on-premises LDAP directories.
That distinction matters.
Organizations must answer three key questions:
- How do we authenticate users with an existing corporate identity system?
- How do we map authenticated users to AWS permissions?
- How do we avoid long-lived AWS credentials?
AWS identity federation provides the solution.
The Recommended Solution: AWS Identity Federation with an Identity Broker
In real-world AWS architectures, teams solve this problem by introducing an identity broker.
Instead of asking AWS to authenticate users directly, the organization:
- Authenticates users externally
- Authorizes access inside AWS using IAM roles
This separation aligns with AWS security best practices and enterprise security requirements.
How AWS Identity Federation Works (Step by Step)
- A user signs in using corporate credentials.
- The identity broker authenticates the user against LDAP or Active Directory.
- The broker determines which AWS IAM role the user can assume.
- The broker calls AWS Security Token Service (STS).
- AWS STS issues temporary security credentials.
- The user accesses AWS resources using those credentials.
AWS never stores passwords, and the system never creates long-lived IAM users.
Reference Architecture
User
→ Identity Broker
→ Corporate LDAP / Active Directory
→ AWS STS (AssumeRole)
→ Temporary Credentials
→ AWS Resources
This architecture supports:
- AWS Management Console access
- AWS CLI and API usage
- Automation tools such as Terraform and CI/CD pipelines
Why This AWS Identity Federation Architecture Works
1. Security by Design
- Temporary credentials expire automatically.
- IAM roles enforce least-privilege access.
- AWS never stores corporate passwords or secrets.
This approach significantly reduces credential exposure and attack surface.
2. Operational Simplicity
- Teams manage identities in one centralized system.
- Role-based access replaces individual IAM users.
- AWS CloudTrail records every access attempt for auditing.
This design prevents IAM user sprawl and simplifies governance.
3. Scalability for Enterprise Environments
- Organizations onboard and offboard users quickly.
- The model scales from small teams to large enterprises.
- Hybrid and VPN-connected environments integrate cleanly.
When to Use AWS Identity Federation
This approach works best when:
- An organization already uses LDAP or Active Directory
- Teams want a single identity source for cloud and on-premises systems
- The environment includes hybrid connectivity
- Security teams require centralized authentication control
Conclusion: Secure and Scalable AWS Access Without Identity Silos
AWS identity federation does more than improve convenience—it reduces risk while enabling scale.
By separating authentication from authorization and using IAM roles with temporary credentials, organizations can adopt AWS without introducing new identity silos or managing long-lived secrets.
This pattern follows AWS security best practices, supports enterprise governance, and delivers a clean, scalable identity architecture that works in real-world environments.