These kinds of questions are way too specific for a Digital Nomad community. I see you’ve asked a bunch of them, so I felt compelled to address the meta-problem of where to ask questions.
First, is “VPS setup” related to digital nomading? Not really. Even if you meant “VPN”, not “VPS”, there are communities better targeted at security.
Second, the whole NomadGate community has ~5000 members, of which only a small portion are active - I’d wager under 1%. Become familiar with this concept; it’s very important when it comes to online communities:
Next, how many people here do you think use Linux? Most DNs are Mac users, some use Windows. Linux? Maybe 1%? 10% tops. Let alone that you’ve asked about CentOS specifically.
So 10% of 1% of 5000 members, if we’re being generous. A grand total of 5 people here who might be using Linux - but does that mean they know how what the heck NS~A/FB~I proof Encrypted file-system/hard-disk/partition means?
I’ve been using Linux since '94, have a degree in CS, develop web apps for a living, have been using encryption and VPNs for over 15 years, and have no idea what that is.
So long story short, use specialized Q&A sites for your niche questions that aren’t specific to digital nomading (Bitcoin mining, Android security and whatnot).
In this case, VPNs/VPS:
- https://security.stackexchange.com (probably your best bet)
- https://askubuntu.com - Ubuntu - specific
- https://unix.stackexchange.com - Unices in general
- https://superuser.com
Type your question in all of them via Ask New Question, and see what related questions are most relevant. Then ask in only one of the sites.