An Essential Guide to Linux Security for Beginners! This publication is not about starting with Linux, but about initiating security practices within the Linux environment. Inside, you will find essential information on securing your personal Linux computer. Although in the publication, immunized distributions are recommended, you can successfully apply the advice in Debian and distributions based on it like Ubuntu, Mint, and others, as well as in the non-immunized Fedora Linux! Topics discussed in the book: - security - Fedora Silverblue - NixOS - Qubes OS - installation - configuration - privacy - VPN - web browsers - HTTPS. The second edition has been supplemented with the following topics: - monitoring services running on the UDP protocol using the nmap command, - the AppArmor module, - a tip for Flatpak users, - the difference between using apt and apt-get to update Debian-based systems, - disabling the ability for someone to ping the computer using ICMP, and more.