Everyone who is interested in computing, information technology, and / or information security should learn about Linux. While the history is interesting; the best way to do that is by downloading, installing, and using it. For generalists I suggest Ubuntu. If you are interested in learning about network and cyber security I suggest Security Onion and Kali Linux distros (distributions). These are my notes to anyone starting that journey.
Once you’ve decided which distro you want to learn and before you download the image you should consider install options.
You have several installation choices but they break down into two categories: bare metal or virtual. If you have a computer on which you want to run Linux all the time; you can install it directly on pretty much any old computer. People call this a bare metal install because the Linux software is interacting directly with your computer hardware.
The other method is virtual running on top of either another operating system (Windows or Mac) or on virtualization software (Oracle VirtualBox or VMware ESX).
My suggestion is go virtual. I run Linux on my work and on my personal Macs; both using desktop virtualization software specifically VMware Fusion. If you are using a Windows operating system you have more choices. Both Oracle VirtualBox and VMware Workstation are available for Windows 10.
Another way of going is to install VMware ESXi on a server and create a Linux virtual machine. That’s a great way of learning not only about Linux but also virtualization. If you can get access to VMware ESX for your make and model of server you’ll be able to learn much more about virtualization than using ESX.
Where to find a Linux distribution.
Google is often your friend, If you Google ‘Ubuntu download’ the first hit will likely be the Ubuntu Software Center. First decision you need to make is whether to install the Desktop or the Sever version. If you are just getting started let me suggest the Desktop. The hardware requirements for Desktop are less and it installs a graphical user interface by default.
It’s the same for Kali and Security Onion. Kali points to the Kali Linux Downloads page and the Security Onion is available at Security Onion dot net. Both of these distributions are very well documented and again using Google search you can find plenty of videos to help install and understand basic, and in some cases advanced uses for each product.
If you are interested in Internet security from the defense or blue team perspective I suggest getting started with SecurityOnion and ELK (Elastic Logstash Kibana). Versions of Security Onion dated after 2018 have the ELK stack installed and well configured by default.