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

Using SELinux Boolean settings to enable services

Many services have a wide range of configuration options for many common cases, but not always the same. For example, the http server should not access user files, but at the same time, it’s a common operation to enable personal websites from the www or public_html folders in each user’s home directory.

To overcome that use case and at the same time, provide enhanced security, the SELinux policy makes use of Booleans.

A Boolean is a tunable that can be set by the administrator that can enable or disable conditionals in the policy code. Let’s see, for example, a list of Booleans available for httpd by executing getsebool -a|grep ^http (list reduced):

httpd_can_network_connect --> off
httpd_can_network_connect_db --> off
httpd_can_sendmail --> off
httpd_enable_homedirs --> off
httpd_use_nfs --> off

This list is a reduced subset of the Booleans available, but it does give us an idea of what...