Written by Chris Koh, DevOps Engineer at TrackIt
Identity and access management is a cornerstone of a robust AWS security posture. As organizations expand their cloud footprint, ensuring that only the right users have access to critical resources is paramount. AWS offers two primary solutions for managing identities: IAM (Identity and Access Management), which provides granular control over permissions within individual accounts, and IAM Identity Center (formerly AWS Single Sign-On or AWS SSO), which simplifies user authentication and centralizes access across multiple accounts and applications.
IAM is a standard feature in every AWS account and cannot be removed. It serves as the foundation for access control across AWS environments, whereas IAM Identity Center is an optional service that enhances user authentication and management but does not replace IAM entirely. Even when IAM Identity Center is used, IAM remains critical for defining permissions and managing access to AWS resources. Additionally, best practices dictate that there should always be at least two IAM users: the root user, which should be reserved for emergencies, and at least one administrator account to ensure secure and continuous access management.
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What is IAM?
AWS Identity and Access Management (IAM) is the core authentication and authorization framework used across all AWS accounts. It enables organizations to define who can access AWS resources and what actions they can perform. IAM provides a flexible permissions model that allows for precise access control through users, groups, roles, and policies.
Key Features of IAM
- User and Group Management – Create IAM users and organize them into groups with predefined permissions.
- Roles and Policies – Assign IAM roles to AWS resources and use policies to define the exact level of access allowed.
- Federation Support – Integrate IAM with external identity providers (IdPs) using SAML or OpenID Connect.
- Granular Permission Control – Enforce fine-grained access control through JSON-based policies that restrict actions at the resource level.
Common Use Cases for IAM
- Managing user access and permissions within a single AWS account.
- Assigning specific service permissions to AWS workloads via IAM roles.
- Implementing the principle of least privilege by defining restrictive policies.
- Enabling programmatic access to AWS services through IAM users and access keys.
- Managing service-to-service authentication by allowing AWS services to interact securely via IAM roles.
Common Issues with IAM
Despite its powerful capabilities, IAM can present challenges, particularly in growing AWS environments:
- Policy Complexity – IAM policies are written in JSON and can be difficult to manage, debug, and audit as environments grow.
- Permissions Creep – Over time, users and roles may accumulate more permissions than necessary, increasing security risks.
- Account Silos – When using IAM alone, managing access across multiple AWS accounts can be complex and inefficient.
IAM is fundamental to AWS security, but as organizations scale and adopt multi-account strategies, additional tools like IAM Identity Center may be necessary to simplify access management and improve administrative efficiency.
What is IAM Identity Center?
IAM Identity Center is an AWS service designed to simplify user authentication and access management across multiple AWS accounts and third-party applications. It provides a centralized way to manage user identities and their access permissions, making it easier for organizations to enforce security policies and reduce administrative overhead. Unlike IAM, which requires managing individual users and roles within each AWS account, IAM Identity Center enables single sign-on (SSO) across multiple AWS accounts and integrated applications.
Key Features of IAM Identity Center
- Centralized User Authentication – Manage user access to multiple AWS accounts and applications from a single interface.
- Seamless SSO Experience – Users log in once and gain access to authorized AWS accounts and cloud applications without needing multiple credentials.
- Integration with External Identity Providers – IAM Identity Center supports federated authentication with services like Okta, Microsoft Entra ID (Azure AD), Ping Identity, and others.
- Group-Based Access Control – Assign permissions at scale by managing users in groups rather than assigning permissions individually.
- Temporary Credentials – Unlike IAM users who may use long-lived access keys, IAM Identity Center provides short-term credentials, reducing security risks.
Common Use Cases for IAM Identity Center
- Managing access to multiple AWS accounts within an AWS Organization from a single dashboard.
- Providing federated authentication for users via an external identity provider instead of manually creating IAM users.
- Reducing the need for long-term IAM credentials by enabling users to assume temporary roles instead of using static IAM access keys.
- Simplifying access control for non-technical users who need AWS access without complex IAM policy configurations.
When to Use IAM
IAM remains the core identity and permissions system in AWS, even when IAM Identity Center is used. There are several scenarios where IAM is the preferred or necessary choice over IAM Identity Center:
- Single AWS Account Management – If your organization operates primarily within a single AWS account, IAM provides sufficient access control without requiring IAM Identity Center. However, operating in a single AWS account is not best practice especially in a workplace setting.
- Fine-Grained Permission Management – IAM allows for detailed, resource-level permissions with granular conditions (e.g., time-based access, IP restrictions, or MFA enforcement).
- Programmatic Access & Service-to-Service Authentication – Many AWS services and applications require IAM roles to interact securely.
- Third-Party Software & Legacy Systems – Some applications and workloads rely on IAM users and access keys for authentication.
- Emergency Access – Even if an organization primarily uses IAM Identity Center, IAM should always retain at least two users: the root user and one administrator to ensure emergency access if IAM Identity Center becomes unavailable.
When to Use IAM Identity Center
IAM Identity Center is ideal for organizations that need centralized user authentication, multi-account management, and seamless identity provider integration.
- Multi-Account Access Management – Provides centralized authentication across multiple AWS accounts.
- Integration with External Identity Providers – Supports Okta, Microsoft Entra ID (Azure AD), and other IdPs.
- Improved User Experience – Users log in once and gain access to assigned AWS accounts and applications.
- Group-Based Access Control – Permissions are managed at the group level rather than per user.
- Minimizing IAM User Management – Reduces reliance on long-term IAM credentials.
Although it is more suitable for larger or more complex account structures, if you ever plan to scale your account, it’s best to put the processes in place now. If you use IAM for a year before switching to IAM Identity Center, that’s a year’s worth of policies and configurations to account for during migration, plus learning an entirely new system. Starting with IAM Identity Center ensures you’re ready to scale at any time.
Implementation Best Practices
- Use IAM for administrative and programmatic access.
- Adopt IAM Identity Center for centralized user authentication.
- Maintain at least two IAM users (root user and an administrator).
- Follow the principle of least privilege.
- Regularly audit permissions.
- Plan for scalability.
Closing Thoughts
IAM and IAM Identity Center serve distinct but complementary roles in AWS identity management. For single-account environments, fine-grained permission control, and programmatic access, IAM is often sufficient. However, for multi-account setups, centralized authentication, and integration with external identity providers or for single accounts that plan to scale IAM Identity Center is the better choice.
About TrackIt
TrackIt is an international AWS cloud consulting, systems integration, and software development firm headquartered in Marina del Rey, CA.
We have built our reputation on helping media companies architect and implement cost-effective, reliable, and scalable Media & Entertainment workflows in the cloud. These include streaming and on-demand video solutions, media asset management, and archiving, incorporating the latest AI technology to build bespoke media solutions tailored to customer requirements.
Cloud-native software development is at the foundation of what we do. We specialize in Application Modernization, Containerization, Infrastructure as Code and event-driven serverless architectures by leveraging the latest AWS services. Along with our Managed Services offerings which provide 24/7 cloud infrastructure maintenance and support, we are able to provide complete solutions for the media industry.