My Journey With Linux (1)

This article serves to discuss my progress with learning and using Linux, specifically for cybersecurity functions, which covers the basics as well. Please note that I am still learning about Linux and its many features. Although I am not an expert, but I hope to be one day, and wanted to pass along the knowledge that I have gained so far.

What is Linux?

For those who don't know, Linux is a different computer operating system. Most operating systems that people are familiar with are Windows and Mac OS. Linux is different on many levels, but primarily because most of the Linux flavors are free to download and install, and also that it is open source. Open source basically means that the details of the program are openly available to the public. This allows users to inspect the code within the Operating System. This helps with finding bugs or loopholes faster by users reporting these features and then the makers of the Linux flavor can distribute a patch to fix security holes.

When I say flavors, it just means the different versions of the Linux distributions that are available. Some common ones are Ubuntu, Mint, Red Hat, and Kali just to name a few. My journey originally started by setting up an Ubuntu virtual machine, but feel free to start with any flavor that suits you.

How do I access Linux?

I had heard about Linux for many years. Only this year I decided to tinker with it and learn how to use it. I downloaded a version of Linux called Ubuntu. I run it on my laptop at home using a program called Oracle VirtualBox. It's pretty exciting. VirtualBox allows me to run a virtual computer (like a computer within a computer) on my Windows 10 laptop. There are other programs that allow virtualization, but I chose to run with VirtualBox and I'm happy with using it so far. The first time installing an OS on VirtualBox can take a while, but there are plenty of guides on the internet to help you get started. Each additional Virtual Machine (VM) you add after your first will get easier and easier to install the more you do it.

Current versions of Ubuntu are very easy to use. The current version at the time of writing this post is 20.04.3. After going through the installation process, I was able to see a desktop with icons on the side that looked quite similar to a Mac desktop or even Windows. I could click on icons to open up the apps. This style of navigating is called using the GUI (Graphical User Interface). That was well and fun, but I started to learn how to use the terminal to run commands. Based on research and feedback from others, it wasn't always so easy and required a bit of advanced learning. From my understanding, older versions of Ubuntu used to require users to utilize the terminal and didn't even contain a GUI. This has helped me in transitioning from primarily a Windows user to a Linux user. And the more I use Linux, the more I've been using the Command Line Interface (CLI or also referred to as the terminal). The CLI is where the real power is within computing.

Tell me more about this terminal

So far I've mostly been using basic commands in the Linux terminal, but they prove to be very useful and can still be utilized for certain security purposes. The ones I've been using a lot of are cd, ping, pwd, ip a, mkdir, vi (+file name), vim (+file name), cd .. , shutdown, cp, mv, chmod, and passwd.

• cd = it stands for "change directory" and allows a user to navigate to different directories/folders and locations within the computer
• ping = ping is a common network communication tool used to see if there is connectivity between computers
• pwd = it stands for "print working directory". If after navigating a lot, it can help to check which full directory path you're currently sitting in. From a security standpoint, it can be helpful to check command history from admin level users from time to time. If there were a lot of pwd commands issued, it could be an attacker trying to navigate through your system
• ip a = the command has been adjusted overtime, but currently "ip a" is a command used to check your IP configuration settings. This allows you to view your current IP address(es) and to see which network interfaces are available
• mkdir = it stands for "make directory". Again, if you're more familiar with Windows or Macs, this would be the same as creating a folder
• vi = opens a text editor named vi. If you place a filename after the vi command it will open that file, and if the file doesn't yet exist, it will create a new file by that name and immediately open the vi program for you to create your text file
• vim = opens a text editor named vim
• cd .. = the .. after cd allows the user to navigate one directory backwards
• shutdown = this is the method of shutting down the computer from the CLI
• cp = it stands for copy and as the name states, allows you to make a copy. The format is by typing the command, then the original file name, then the name for the copy of the file. Example; cp file1.txt file1-copy.txt
• mv = it stands for move and as the name states, it allows you to move a file. This can also be used to rename a file if chosen. The format is by typing the command, then the original file name and location, then the name and location where you want it moved. Example; mv /home/jim/Desktop/file1.txt /home/jim/file-pasted.txt
• chmod = it stands for "change mode" and allows the user to set permissions on files or directories. This is especially useful for security purposes. You can adjust who is able to read, write, or execute files, which you definitely want to control for sensitive files and directories
• passwd = it stands for "password" and allows a user who is authorized to do so, to change the password of a user account

One more command I want to mention that I've been using is grep. The command is extremely useful for locating specific strings of text within files. The grep command could basically have a whole article to itself as there are so many adjustments that can be done with the command to provide different output or structure to it. As a quick example, if you had a file with lots of text in it, but you only wanted to find a specific line of text, perhaps one that included the word "error", you could easily find each instance that the word "error" appeared in the file. The command you run could be as basic as; grep "error" file1.txt. This would output each line that contains the word "error". It may include lines that only have the word or lines that had a sentence with the word error in the middle of it. From a security standpoint, you might use a search like this on particular log files while searching for what kinds of errors occurred and were logged. Finding such information could help lead to a root cause and allows you to fix the main problem.

Conclusion

My experience thus far has been great and I really enjoy using Linux. There are many CLI tools that can be accessed through the terminal and the more I continue to use and practice it the better I get. It's definitely different from Windows if that's what you're used to using like I was, but don't let the stop you from trying out and learning how to use Linux. Afterall, it's a common OS utilized for cybersecurity and IT devices, so knowing how to use Linux will definitely help you if you venture into these specific fields.

Thanks for reading about my journey with Linux. See you next time.