Setting up FreeIPA on CentOS 8

01/09/2025

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Mastering Centralized Authentication: A Step-by-Step Guide to Installing FreeIPA on CentOS 8

Managing user identities, authentication, and access policies across a fleet of Linux servers can quickly become a complex and error-prone task. Without a centralized system, you’re left juggling local user accounts on each machine—a scenario that is neither scalable nor secure. This is where a robust Identity Management (IdM) solution becomes essential.

FreeIPA is a powerful, open-source identity management solution for Linux environments. It integrates several core services—including a 389 Directory Server (for LDAP), MIT Kerberos, NTP, DNS, and a Dogtag certificate system—into a single, cohesive platform. By deploying FreeIPA, you can create a centralized authentication server that simplifies user management, enforces consistent security policies, and provides a reliable single sign-on (SSO) experience.

This comprehensive guide will walk you through the entire process of installing and configuring a FreeIPA server on CentOS 8.

Before You Begin: Essential Prerequisites

A successful FreeIPA installation depends on a correctly prepared environment. Neglecting these initial steps is the most common source of installation failures.

System Requirements: Ensure your server meets the minimum requirements. For a small to medium-sized environment, at least 4 GB of RAM and 2 CPU cores are recommended.
Static IP Address: Your FreeIPA server must have a static IP address. Dynamic IPs will cause service failures.
Fully Qualified Domain Name (FQDN): The server must have a proper hostname set. This should be an FQDN (e.g., ipa.yourdomain.com). You can set this using the hostnamectl command:
bash sudo hostnamectl set-hostname ipa.yourdomain.com
/etc/hosts Configuration: You must add an entry in your /etc/hosts file that maps the server’s static IP address to its FQDN and short hostname. This is crucial for local name resolution during the setup process.
# Example /etc/hosts entry 192.168.1.100 ipa.yourdomain.com ipa
System Updates: Ensure your system is fully up to date by running a system-wide update.
bash sudo dnf update -y

Step 1: Installing the FreeIPA Server Packages

With the prerequisites in place, the first step is to install the necessary FreeIPA packages from the CentOS repositories. The ipa-server package is required, and it’s highly recommended to also install ipa-server-dns if you want FreeIPA to manage DNS for your domain, which simplifies client configuration significantly.

Execute the following command to install the packages:

sudo dnf install ipa-server ipa-server-dns -y

This command will download and install the FreeIPA server, its dependencies, and the integrated DNS service components.

Step 2: Running the Interactive Installation Script

The core of the configuration process is handled by an interactive script. This script will ask a series of questions to configure the directory server, Kerberos realm, DNS, and administrative accounts.

To begin the installation, run the following command as the root user or with sudo:

sudo ipa-server-install --setup-dns

The script will guide you through several configuration prompts. Pay close attention to the following values:

Server Hostname: This should be automatically detected from your system’s FQDN.
Domain Name: This is your base domain (e.g., yourdomain.com).
Realm Name: By convention, the Kerberos Realm is the domain name in uppercase (e.g., YOURDOMAIN.COM).
Directory Manager Password: This is the superuser password for the underlying LDAP directory. Store this password in a secure location, as it is needed for deep recovery and maintenance tasks.
IPA Admin Password: This is the password for the primary FreeIPA administrator account (username: admin). You will use this account for day-to-day management through the Web UI and command line.

The installer will ask for confirmation before proceeding with the configuration. Double-check all the values before typing yes. The process will take several minutes as it configures all the necessary services.

Step 3: Finalizing and Verifying Your Installation

Once the installation script completes successfully, you must perform a few final steps to secure and verify the system.

Configure Firewall Rules: The installation script automatically opens the necessary ports in the system’s active firewalld configuration. However, you need to make these rules permanent so they persist after a reboot.
Run the following command to reload the firewall and apply the permanent rules:
```
sudo firewall-cmd --reload
```
Key services allowed include http, https, ldap, ldaps, kerberos, and dns.
Authenticate via Kerberos: The first and most important verification step is to obtain a Kerberos ticket for the admin user. This confirms that the authentication service is working correctly.
```
kinit admin
```
You will be prompted to enter the IPA Admin Password you set during installation. If the command succeeds without errors, your authentication backend is operational. You can view your active ticket with the klist command.
Access the FreeIPA Web UI: You can now manage your FreeIPA server through a user-friendly web interface. Open a web browser and navigate to your server’s FQDN:
https://ipa.yourdomain.com
You may see a browser warning due to the self-signed SSL certificate created during installation. Proceed past the warning and log in with the username admin and the IPA Admin Password.

Essential Security and Management Tips

With your FreeIPA server now online, follow these best practices:

Create Dedicated User Accounts: Avoid using the powerful admin account for routine tasks. Use the Web UI or command line to create new users and delegate specific permissions using roles.
Regular Backups: Your FreeIPA server is a critical piece of infrastructure. Implement a regular backup schedule using the ipa-backup utility to protect your identity data.
Enroll Client Machines: The real power of FreeIPA is realized when you enroll your other Linux servers and workstations as clients. This enables centralized login, sudo policy management, and more.
Explore Host-Based Access Control (HBAC): Use HBAC rules to define which users and groups are allowed to access specific client machines, providing granular control over your entire environment.

By successfully deploying FreeIPA, you have built a powerful foundation for a scalable, secure, and easily manageable Linux infrastructure.

Source: https://kifarunix.com/install-and-setup-freeipa-server-on-centos-8/