In the era of hyper-distributed systems where AI agents traverse our networks, and hybrid clouds stretch from the edge to the core, the "who" and "what" of infrastructure access are more critical than ever. Managing identities across thousands of nodes is a vital administrative task in optimizing your infrastructure's security posture. To assist with this, Red Hat Identity Management (IdM) can serve as a comprehensive domain controller for your Linux environment. If you're still managing local /etc/passwd files, or struggling with complex cross-realm Kerberos trusts manually, then it's time to adopt IdM.What is identity management?You might think of IdM (based on the upstream FreeIPA project) as a solution similar to Active Directory, but IdM is designed specifically for the Linux ecosystem, and even more specifically for distros with sssd. IdM provides a centralized suite of services, and can manage:Authentication: Who can log in (using Kerberos and LDAP)Authorization: What they can do (using Host-Based Access Control and sudo rules)Policy: Enforcing password complexity and security standards globallyCentralized identities: Storing user, group, and host information in one placeInfrastructure that's AI-readyTwo major shifts in the IT industry are redefining IdM's role in infrastructure.1. Red Hat Enterprise Linux 10 and OS-as-a-ContainerRed Hat Enterprise Linux 10 features an image mode that treats your operating system (OS) like a container, giving you a fast, immutable, and scalable OS image. IdM plays a vital role in this by providing a stable, external identity layer that persists even when your immutable OS image is swapped and updated.2. Automation with Red Hat Ansible Automation PlatformWith Red Hat Ansible Automation Platform, manually running ipa-server-install is a thing of the past. The redhat.rhel_idm collection (the ansible-freeipa collection in the AppStream repository) is available in the Red Hat automation hub, and has become the standard way to deploy and manage IdM. Today, we treat infrastructure as code when scaling IdM replicas across multiple cloud providers automatically, ensuring that identity is never a bottleneck for your scaling apps.Top 7 features of IdMTwo-factor authentication (2FA): Native support for smart cards and one-time password (OTP) systems such as FreeOTP and Google Authenticator. You get zero-trust security without needing a third-party proprietary vault.Active Directory (AD) trust: Creates a bridge between Linux IdM and Microsoft Active Directory, so users can log in with Windows credentials but Linux admins keep control of Linux policies.ID views: Overrides user identifier (UID) and group identifier (GID) numbers for specific clients. Migrate legacy systems with conflicting user IDs without breaking. permissions.Certmonger: Automatically requests and renews secure sockets layer (SSL) and transport layer security (TLS) certificates for services. No more "expired certificate" outages at 3 AM!Automatic Certificate Management Environment (ACME) service: Automated issuing of certificates to reduce certificate lifetimes and manual administration of certificate lifecycle.Policy and access control: HBAC rules (host + service + user access policies) and centralized sudo policies for reduced dependency of ad-hoc scripts and centralized definitions. Enforce consistent policies at scale.Automation and API: Command-line tools (ipa commands) for admins, REST API for automation, Ansible automation. You can integrate tooling using the API, and use Ansible playbooks to manage your environment.Top 3 tips for setting up your deploymentIf you're setting up or upgrading your IdM environment today, keep these three rules in mind:Plan for replicas: Never run just one IdM server. Aim for at least two per data center or cloud region for high availability and load balancing. Also, consider at least one hidden replica to use to perform service operations that could impact clients, such as offline full backups.Use the upgrade helper: When upgrading from Red Hat Enterprise Linux 9 to Red Hat Enterprise Linux 10, use the IdM upgrade helper app, available from Red Hat Customer Portal Labs. It helps you manage the transition by adding Red Hat Enterprise Linux 10 replicas and decommissioning old Red Hat Enterprise Linux 9 nodes.Pro tip: Before you start your Red Hat Enterprise Linux 10 migration, run ipa-healthcheck. It's the easiest way to catch replication errors or DNS issues before they become "site down" events.Integrate with security information and event management (SIEM): Use IdM's centralized logging to feed your security dashboards. Knowing exactly when a user's password was changed or when a sudo command was denied across 500 servers is invaluable for compliance.Improve your infrastructureIdentity Management is not just a "nice to have" feature. It's a key component of a modern Linux estate. By centralizing identities, you reduce your attack surface while simplifying management and audits.Are you ready to move away from local user management, ad-hoc scripts, and legacy authentication to embrace a unified domain? Discuss with your Red Hat Technical Account Manager or connect with Red Hat Consulting to learn how we can support your organization with all of your Red Hat Enterprise Linux needs. In addition, Red Hat Training and Certification is available for your learning needs. Specifically, Red Hat Security: Identity Management and Authentication (RH362) provides course content for configuring and managing IdM.