Book Image

Mastering Linux Security and Hardening - Third Edition

By : Donald A. Tevault
3.7 (7)
Book Image

Mastering Linux Security and Hardening - Third Edition

3.7 (7)
By: Donald A. Tevault

Overview of this book

The third edition of Mastering Linux Security and Hardening is an updated, comprehensive introduction to implementing the latest Linux security measures, using the latest versions of Ubuntu and AlmaLinux. In this new edition, you will learn how to set up a practice lab, create user accounts with appropriate privilege levels, protect sensitive data with permissions settings and encryption, and configure a firewall with the newest firewall technologies. You’ll also explore how to use sudo to set up administrative accounts with only the privileges required to do a specific job, and you’ll get a peek at the new sudo features that have been added over the past couple of years. You’ll also see updated information on how to set up a local certificate authority for both Ubuntu and AlmaLinux, as well as how to automate system auditing. Other important skills that you’ll learn include how to automatically harden systems with OpenSCAP, audit systems with auditd, harden the Linux kernel configuration, protect your systems from malware, and perform vulnerability scans of your systems. As a bonus, you’ll see how to use Security Onion to set up an Intrusion Detection System. By the end of this new edition, you will confidently be able to set up a Linux server that will be secure and harder for malicious actors to compromise.
Table of Contents (22 chapters)
1
Section 1: Setting up a Secure Linux System
9
Section 2: Mastering File and Directory Access Control (DAC)
12
Section 3: Advanced System Hardening Techniques
20
Other Books You May Enjoy
21
Index

Understanding journald

You’ll find the journald logging system on any Linux distro that uses the systemd ecosystem. Instead of sending its messages to text files, journald sends messages to binary files. Instead of using normal Linux text file utilities to extract information, you have to use the journalctl utility. At the time of writing, I don’t know of any Linux distro that has made the complete transition to journald. Current Linux distros that use systemd run journald and rsyslog side by side. Currently, the default on RHEL-type systems is for journald log files to be temporary files that get erased every time you reboot the machine. (You can configure journald to make its log files persistent, but there’s probably not much point as long as we still need to keep the old rsyslog files.) On Ubuntu, the default is for both journald and rsyslogd to maintain persistent log files.

On RHEL 8/9-type distros, journald, instead of rsyslog, is now what actually...