Book Image

Linux for System Administrators

By : Viorel Rudareanu, Daniil Baturin
Book Image

Linux for System Administrators

By: Viorel Rudareanu, Daniil Baturin

Overview of this book

Linux system administration is an essential aspect of maintaining and managing Linux servers within an organization. The role of a Linux system administrator is pivotal in ensuring the smooth functioning and security of these servers, making it a critical job function for any company that relies on Linux infrastructure. This book is a comprehensive guide designed to help you build a solid foundation in Linux system administration. It takes you from the fundamentals of Linux to more advanced topics, encompassing key areas such as Linux system installation, managing user accounts and filesystems, networking fundamentals, and Linux security techniques. Additionally, the book delves into the automation of applications and infrastructure using Chef, enabling you to streamline and optimize your operations. For both newcomers getting started with Linux and professionals looking to enhance their skills, this book is an invaluable hands-on guide with a structured approach and concise explanations that make it an effective resource for quickly acquiring and reinforcing Linux system administration skills. With the help of this Linux book, you’ll be able to navigate the world of Linux administration confidently to meet the demands of your role.
Table of Contents (21 chapters)
Part 1: Linux Basics
Part 2: Configuring and Modifying Linux Systems
Part 3: Linux as a Part of a Larger System

Authentication mechanisms in Linux

Before we learn about centralized authentication mechanisms, we need to learn how authentication works in Linux in general. Before a system can check user credentials, it needs to fetch user information first – let’s examine how information lookup works.

Information lookup

Information about users and groups is necessary for authentication, but it has many other uses. For example, file ownership information is usually displayed in a human-readable fashion, but internally, filesystems store numeric user and group identifiers, so even programs that have nothing to do with security, such as ls, may need to have a way to look up information about users and groups to map their identifiers to names.

The POSIX API standard includes multiple functions for querying information about various entities such as users, groups, and hosts. For example, gethostbyname(name) retrieves network addresses associated with a domain name, and getgrpnam...