RHEL Complete Enterprise Linux Guide

RHEL Complete Enterprise Linux Guide | Generated by AI

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Here’s a comprehensive guide to Red Hat Enterprise Linux (RHEL). I’ll structure it step by step so you can use it as both a learning path and a reference.

1. Introduction to Red Hat Linux

Red Hat Enterprise Linux (RHEL) is a commercial Linux distribution developed by Red Hat, Inc., designed for stability, security, and enterprise support. It is widely used in banking, healthcare, government, and corporate IT because of its long-term support lifecycle and certified software ecosystem.

Key highlights:

Enterprise-grade support (10+ years lifecycle per major release).
Certified on major hardware (Dell, HP, IBM, etc.).
Widely used in cloud (AWS, Azure, GCP), containers (OpenShift, Kubernetes), and virtualization.

2. Installation and Setup

Download: Official ISO images are available via Red Hat Customer Portal (requires subscription).
Installers: Uses the Anaconda installer with graphical and text modes.
Partitioning: Options for LVM, XFS (default filesystem), and encrypted disks.
Post-installation tools: subscription-manager for registering the system.

3. Package Management

RPM (Red Hat Package Manager) – the underlying format for software.
DNF (Dandified Yum) – the default package manager in RHEL 8 and later.
- Install a package:
```
sudo dnf install httpd
```
- Update system:
```
sudo dnf update
```
- Search packages:
```
sudo dnf search nginx
```

RHEL also supports AppStreams for multiple versions of software (e.g., Python 3.6 vs 3.9).

4. System Administration Basics

User Management: useradd, passwd, usermod, /etc/passwd, /etc/shadow
Process Management: ps, top, htop, kill, systemctl
Disk Management: lsblk, df -h, mount, umount, fdisk, parted

System Services (systemd):

systemctl start nginx
systemctl enable nginx
systemctl status nginx

5. Networking

Configuration stored in /etc/sysconfig/network-scripts/.
Commands:
- nmcli (NetworkManager CLI)
- ip addr, ip route, ping, traceroute

Firewall:

Managed by firewalld (firewall-cmd).

Example:

firewall-cmd --add-service=http --permanent
firewall-cmd --reload

6. Security

SELinux: Mandatory access control system.
- Check status: sestatus
- Modes: enforcing, permissive, disabled
FirewallD: Manages network security.
System Updates: Security patches via dnf update.
Auditd: Logging and compliance.

7. Logging and Monitoring

System logs: Stored under /var/log/.
Journald: journalctl -xe
Performance tools:
- sar (sysstat package)
- vmstat, iostat, dstat
Red Hat Insights: Cloud-based system analysis.

8. Virtualization and Containers

KVM (Kernel-based Virtual Machine) for virtualization.
Podman (instead of Docker):
```
podman run -it centos /bin/bash
```
OpenShift (Kubernetes platform) for orchestration.

9. Storage Management

LVM (Logical Volume Manager) for flexible disk management.
XFS: Default filesystem.
Stratis: Storage management with thin provisioning and snapshots.

10. Automation and Configuration Management

Ansible: Red Hat’s automation platform.
Kickstart: Automates OS installations.
System Roles: Predefined Ansible roles for RHEL.

11. Subscriptions and Support

Red Hat uses a subscription model.
subscription-manager to register, attach subscriptions, and enable repositories.
RHEL developer subscription is free for individuals.

12. Best Practices

Always keep systems updated with security patches.
Use SELinux in enforcing mode unless debugging.
Centralize logging with rsyslog or ELK stack.
Automate repetitive tasks with Ansible.
Monitor system health with Red Hat Insights.

13. Learning Resources

Red Hat Documentation
Red Hat Academy
Certifications:
- RHCSA (Red Hat Certified System Administrator)
- RHCE (Red Hat Certified Engineer)
- RHCA (Red Hat Certified Architect)

✅ That’s the foundation. Would you like me to expand this into a practical “hands-on guide” with real-world commands and workflows (like setting up a web server, database, firewall, etc.), or keep it more theoretical and conceptual?

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