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Red Hat Enterprise Linux 8 Administration

You're reading from   Red Hat Enterprise Linux 8 Administration Master Linux administration skills and prepare for the RHCSA certification exam

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Product type Paperback
Published in Nov 2021
Publisher Packt
ISBN-13 9781800569829
Length 534 pages
Edition 1st Edition
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Authors (3):
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Scott McCarty Scott McCarty
Author Profile Icon Scott McCarty
Scott McCarty
Pablo Iranzo Gómez Pablo Iranzo Gómez
Author Profile Icon Pablo Iranzo Gómez
Pablo Iranzo Gómez
Miguel Pérez Colino Miguel Pérez Colino
Author Profile Icon Miguel Pérez Colino
Miguel Pérez Colino
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Toc

Table of Contents (25) Chapters Close

Preface 1. Section 1: Systems Administration – Software, User, Network, and Services Management
2. Chapter 1: Installing RHEL8 FREE CHAPTER 3. Chapter 2: RHEL8 Advanced Installation Options 4. Chapter 3: Basic Commands and Simple Shell Scripts 5. Chapter 4: Tools for Regular Operations 6. Chapter 5: Securing Systems with Users, Groups, and Permissions 7. Chapter 6: Enabling Network Connectivity 8. Chapter 7: Adding, Patching, and Managing Software 9. Section 2: Security with SSH, SELinux, a Firewall, and System Permissions
10. Chapter 8: Administering Systems Remotely 11. Chapter 9: Securing Network Connectivity with firewalld 12. Chapter 10: Keeping Your System Hardened with SELinux 13. Chapter 11:System Security Profiles with OpenSCAP 14. Section 3: Resource Administration – Storage, Boot Process, Tuning, and Containers
15. Chapter 12: Managing Local Storage and Filesystems 16. Chapter 13: Flexible Storage Management with LVM 17. Chapter 14: Advanced Storage Management with Stratis and VDO 18. Chapter 15: Understanding the Boot Process 19. Chapter 16: Kernel Tuning and Managing Performance Profiles with tuned 20. Chapter 17: Managing Containers with Podman, Buildah, and Skopeo 21. Section 4: Practical Exercises
22. Chapter 18: Practice Exercises – 1 23. Chapter 19: Practice Exercise – 2 24. Other Books You May Enjoy

Learning about time synchronization with chrony and NTP

In this section, you will understand the importance of time synchronization and how to configure the service.

With connected systems, it is important to keep a source of truth in regards to timing (think about bank accounts, incoming transfer wires, outgoing payments, and more that must be correctly timestamped and sorted). Also, consider tracing logs between users connecting, issues happening, and so on; they all need to be in sync so that we can diagnose and debug between all the different systems involved.

You might think that the system clock, which is defined when the system is provisioned, should be OK, but setting the system clock is not enough as the clocks tend to drift; internal batteries can cause the clock to drift or to even reset, and even intense CPU activity can affect it. To keep clocks accurate, they need to be regularly synced against a reference clock that fixes the drift and tries to anticipate future...

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