Summary

In this chapter, we covered in detail the internet basics and network security by explaining OSI and TCP/IP models, network protocol usage, filtering, and attacks. We then reviewed the general advice to increase our security and the various firewall types. Then, we took a detailed look at ufw as a user-friendly firewall, widespread on many Linux distributions. Finally, we took a deep dive into VPNs and how to work with the Surfshark and ExpressVPN clients.

In the following chapter, we will continue with the main services manager on most Linux distributions nowadays – systemd. We will learn about its pros and cons, why it was chosen, and what we can do with it. We will also cover journalctl and daemons. We will continue with user management, as it is one of the greatest strengths of Linux by design. We will conclude the chapter by looking at groups, privileges, ownership, and superuser privileges, all inseparable elements of user management.

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