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

Locking down users’ home directories the Debian/Ubuntu way

Debian and its offspring, such as Ubuntu, have two user creation utilities:

  • useradd
  • adduser

Let’s look at both of them.

useradd on Debian/Ubuntu

The useradd utility is there, but Debian and Ubuntu don’t come with handy preconfigured defaults as the Red Hat-type distros do. If you were to just do sudo useradd frank on a Debian/Ubuntu machine, Frank would have no home directory and would be assigned the wrong default shell. So, to create a user account with useradd on a Debian or Ubuntu system, the command will look something like this:

sudo useradd -m -d /home/frank -s /bin/bash frank

Here’s a breakdown of what all this means:

  • -m creates the home directory.
  • -d specifies the home directory.
  • -s specifies Frank’s default shell. (Without the -s, Debian/Ubuntu would assign to Frank the /bin/sh shell.)

When you look at the...