Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

By : Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty
2 (2)
Book Image

Red Hat Enterprise Linux 9 Administration - Second Edition

2 (2)
By: Pablo Iranzo Gómez, Pedro Ibáñez Requena, Miguel Pérez Colino, Scott McCarty

Overview of this book

With Red Hat Enterprise Linux 9 becoming the standard for enterprise Linux used from data centers to the cloud, Linux administration skills are in high demand. With this book, you’ll learn how to deploy, access, tweak, and improve enterprise services on any system on any cloud running Red Hat Enterprise Linux 9. Throughout the book, you’ll get to grips with essential tasks such as configuring and maintaining systems, including software installation, updates, and core services. You’ll also understand how to configure the local storage using partitions and logical volumes, as well as assign and deduplicate storage. You’ll learn how to deploy systems while also making them secure and reliable. This book provides a base for users who plan to become full-time Linux system administrators by presenting key command-line concepts and enterprise-level tools, along with essential tools for handling files, directories, command-line environments, and documentation for creating simple shell scripts or running commands. With the help of command line examples and practical tips, you’ll learn by doing and save yourself a lot of time. By the end of the book, you’ll have gained the confidence to manage the filesystem, users, storage, network connectivity, security, and software in RHEL 9 systems on any footprint.
Table of Contents (26 chapters)
1
Part 1 – Systems Administration – Software, User, Network, and Services Management
9
Part 2 – Security with SSH, SELinux, a Firewall, and System Permissions
14
Part 3 – Resource Administration – Storage, Boot Process, Tuning, and Containers
21
Part 4 – Practical Exercises

Configuring sudo access for administrative tasks

There is a way to delegate administrative access to users in RHEL, and it is done with a tool called sudo, which stands for Super User Do.

It not only allows you to grant full administrative privileges to users or groups but also to be very granular about the privileged commands that some users may be able to execute.

Let’s start by understanding the default configuration and how to change it.

Understanding sudo configuration

The tool has its main configuration file in /etc/sudoers and includes this part in the default configuration:

root ALL=(ALL)  ALL
%wheel    ALL=(ALL)  ALL
## Read drop-in files from /etc/sudoers.d (the # here does not mean a comment)
#includedir /etc/sudoers.d

Let’s analyze these four specific lines one by one to understand what they do:

  1. The first line enables the root user to use sudo for any command that they want to run:
    root ALL=...