Thank you for the quick response and the help! I am trying to learn Linux for security and pentesting applications, but thank you for the warning. I'm still early on in the process as I'm sure you can tell
May I also just chime in, too. I'm assuming you meant Information Security, which is a large field, of which pentesting is a specialty within. And to be adequate, you need to have a a good knowledge base. I suggest you learn Linux basics first. I'm not talking Ubuntu or <insert distro>, I'm talking fundamentals. You also need a more general understanding of how systems work.
- How the FHS works and why (brief overview: 10 minutes a couple of times until the core is memorised)
- GRUB (since most FOSS bootloaders are are more/less forgotten). You need to be able to confidently edit your GRUB config. Moreover, you need to be able to manually boot your OS from the GRUB shell (ie: selecting storage device, paths to the initramfs, etc. etc.)
- Basic understanding of the boot process: From BIOS/UEFI to your login screen.
- GNU userland (core utilities are a must) and an actual understanding of what happens, say when you move a file, when you use a pipe, when you use a redirect, etc.
You need to understand Information Security, which means things across OSes/systems:
- Basic networking (that's easy)
- Network Security (do a free Comptia N+ "prep" exam online, just to give you an idea of the syllabus, then move on to some up-to-date reading on Network Security as things change more rapidly than exams, which is why doing this through working a company is more ideal; they can further your education while providing the hands-on stuff if, and only if, you can make yourself an asset without butt kissing).
- This all includes Cloud (a game-changer), IoT, etc. So when I said across OSes/systems, I really ment it. And, obviously hardware, too, you need to understand how, as one example, a switch works vs a router.
- Corporate software and appliances (you can probably just get some basics on this, keep up with market trends and changes, know what's out there unless you're planning on becoming a consultant).
You need to understand
what the tools you use do, and
why they do it.
And I'm sure I missed some.
Get an entry-level tech job, work your way up and keep earning qualifications. If you prove yourself to your company, they will pay for or contribute to a lot of your next-level training. Make sure your employment terms include growth potential. As in any job, "you need to be able to say no" which means you have to hold them to their promise if you don't get the growth opportunities you want, i.e. resign and move to another company as scary as it'll be at the time.
^This is all just my unqualified advice. I'm a self-taught technician (and had my own micro-business provide micro services and doing hardware refurbishing), with some development experience, and I now work as a Sales Rep for an IT company, so my knowledge is either from necessity for application-specific tasks, or passive assymilation. If you know people working professionally in Information Security, it may make this a lot easier. They can give you way, way, waaaaay, more qualified advice than I can and direction at each juncture because they're working in the field, they know the most up-to-date trends in IT and Corporate, and they may even be able to help you get jobs.
I don't want to daunt you, but you either need to put in a lot of time, work, or both, depending on your inherent abilities. To provide you with some positivity and inspiration: I know someone who managed to start a hole-in-the-wall IT business that provides consulting, auditing, forensics, and soon Managed Services once he grows his staff compliment and infrastructure, yet he's only turning 25 this year. So if you have aptitude and you're prepared to risk it, you can go for your own business, too., which means building your knowledge while working in IT and taking the dive when ready.
Of course if you just want to be a pentester as a hobby or a freelancer, the distance between two point is a lot closer. You still need an in-depth knowledge of how an OS works, how your OS of choice works, Networking, Information Security, and the tools you'll be using. So it's up to you.
But to reiterate (I like reiteration):
Get comfy with you OS of choice (be that a GNU-based one or anything else) and ancillaries (like GRUB). From there you can decide on the order of your next steps depending on what will, I guess the phrase is, "align with your goals" -- which is such a yuppy phrase, but I can't think of any better prose.
The best of luck to you and I hope it pans out -- and with enough determination it will. This community is great and will always be here. We have some very qualified folk who can help you with anything in your studies. There's a General thread if anything falls outside the other categories, so you can even ask for advice on study materials, courses, etc!
