Book Image

Mastering Ubuntu Server - Fourth Edition

By : Jay LaCroix
5 (4)
Book Image

Mastering Ubuntu Server - Fourth Edition

5 (4)
By: Jay LaCroix

Overview of this book

Ubuntu Server is taking the server world by storm - and for a good reason! The server-focused spin of Ubuntu is a stable, flexible, and powerful enterprise-class distribution of Linux with a focus on running servers both small and large. Mastering Ubuntu Server is a book that will teach you everything you need to know in order to manage real Ubuntu-based servers in actual production deployments. This book will take you from initial installation to deploying production-ready solutions to empower your small office network, or even a full data center. You'll see examples of running an Ubuntu Server in the cloud, be walked through set up popular applications (such as Nextcloud), host your own websites, and deploy network resources such as DHCP, DNS, and others. You’ll also see how to containerize applications via LXD to maximize efficiency and learn how to build Kubernetes clusters. This new fourth edition updates the popular book to cover Ubuntu 22.04 LTS, which takes advantage of the latest in Linux-based technologies. By the end of this Ubuntu book, you will have gained all the knowledge you need in order to work on real-life Ubuntu Server deployments and become an expert Ubuntu Server administrator who is well versed in its feature set.
Table of Contents (26 chapters)
24
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25
Index

Securing OpenSSH

OpenSSH is a very useful utility; it allows us to configure our servers from a remote location as if we were sitting in front of the console. In the case of cloud resources, it’s typically the only way to access our servers. Considering the nature of OpenSSH itself (remote administration), it’s a very tempting target for miscreants who are looking to cause trouble. If we simply leave OpenSSH unsecured, this useful utility may be our worst nightmare.

Thankfully, configuring OpenSSH itself is very easy. However, the large number of configuration options may be intimidating to someone who doesn’t have much experience tuning it. While it’s a good idea to peruse the documentation for OpenSSH, in this section, we’ll take a look at the common configuration options you’ll want to focus your attention on first.

The configuration file for OpenSSH itself is located at /etc/ssh/sshd_config, and we touched on it in Chapter 10,...