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

Auditing files and directories with inotifywait

There might be times when you’ll just want a quick and easy way to monitor a file or a directory in real time. Instead of having audit messages sent to the audit.log file, you can use inotifywait to have a message pop up in your terminal as soon as someone accesses a designated file or directory. This tool is part of the inotify-tools package on both Ubuntu and AlmaLinux. It’s not installed by default, so go ahead and install it if it isn’t already.

To monitor a single file, just do:

donnie@donnie-ca:~$ sudo inotifywait -m /secrets/donnie_file.txt
[sudo] password for donnie: 
Setting up watches.
Watches established.
/secrets/donnie_file.txt OPEN 
/secrets/donnie_file.txt CLOSE_NOWRITE,CLOSE

The /secrets/ directory is set so that only someone with root privileges can access it, so I have to use sudo to make this work. The -m option causes inotifywait to perform continuous monitoring, instead of exiting...