Book Image

Mastering Linux Security and Hardening - Second Edition

By : Donald A. Tevault
Book Image

Mastering Linux Security and Hardening - Second Edition

By: Donald A. Tevault

Overview of this book

From creating networks and servers to automating the entire working environment, Linux has been extremely popular with system administrators for the last couple of decades. However, security has always been a major concern. With limited resources available in the Linux security domain, this book will be an invaluable guide in helping you get your Linux systems properly secured. Complete with in-depth explanations of essential concepts, practical examples, and self-assessment questions, this book begins by helping you set up a practice lab environment and takes you through the core functionalities of securing Linux. You'll practice various Linux hardening techniques and advance to setting up a locked-down Linux server. As you progress, you will also learn how to create user accounts with appropriate privilege levels, protect sensitive data by setting permissions and encryption, and configure a firewall. The book will help you set up mandatory access control, system auditing, security profiles, and kernel hardening, and finally cover best practices and troubleshooting techniques to secure your Linux environment efficiently. By the end of this Linux security book, you will be able to confidently set up a Linux server that will be much harder for malicious actors to compromise.
Table of Contents (20 chapters)
1
Section 1: Setting up a Secure Linux System
8
Section 2: Mastering File and Directory Access Control (DAC)
11
Section 3: Advanced System Hardening Techniques

Setting expiry data on a per-account basis with useradd and usermod

You might find it useful to set the default password expiry data in login.defs, but you probably won't find it too useful to configure the useradd configuration file. Really, what are the chances that you'll want to create all user accounts with the same account expiration date? Setting password expiry data in login.defs is more useful because you'll just be saying that you want new passwords to expire within a certain number of days, rather than to have them all expire on a specific date.

Most likely, you'll want to set account expiry data on a per-account basis, depending on whether you know that the accounts will no longer be needed as of a specific date. There are three ways that you can do this:

  • Use useradd with the appropriate option switches to set expiry data as you create the accounts...