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

Reviewing the SELinux context for files and processes

SELinux uses labels, also referred to as the security context attached to each file, and defines several aspects. Let’s check one example in our home folder with the ls –l command, but with a special modifier, Z, that will show SELinux attributes as well, as we can see in the following screenshot:

Figure 10.3 – File listing showing SELinux attributes

Let’s focus on the output for one of the files:

-rw-r--r--.  1 root unconfined_u:object_r:admin_home_t:s0     540 Mar  6 19:33 term.sh

The SELinux attributes are the ones listed as unconfined_u:object_r:admin_home_t:s0:

  • The first part is the user mapping: unconfined_u
  • The second part is the role: object_r
  • The third part is the type: admin_home_t
  • The fourth part is used for the level: s0 in multi-level security and multi-category security

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