I constantly see people saying "I installed fail2ban" as if that step instantly provides bulletproof security. It doesn't. It's just one layer of basic protection, and a thin one at that.
i would appreciate if you would enlighten us all a bit. give a crash course. i'll pay you for your time. i might even list catcoin if this works out good.
I don't own any catcoin. I was developing a "catcoin" a while ago, but the current one was suddenly "pre-announced" about a week before I was going to release mine. The username was registered a while ago. Also, I doubt it needs to even be said that I wouldn't be registering an account on your exchange any time soon.
You really don't need a crash course, and I'd be doing you and your users a disservice by providing one. You need about 10 years of real world experience running servers that won't end up losing a bunch of peoples' money if they end up breached. Otherwise, you need someone with a lot of experience securing a project like yours working for you full time, and you need them to be able to go over and help you secure your entire app, not just the sysadmin-type stuff.
This is something that should be tested thoroughly in an isolated environment before it ends up anywhere near the internet being used by actual people. When I said what I said about it not being a good idea for someone without the experience to try to do something like this and skip every step in the middle, I wasn't kidding, and I wasn't saying it just to be a dick or crush your dreams. You can't cut corners with something like this.
Start over, create a virtual machine and set it up as a server with your app on it. Encrypt the filesystem on the VM. Distribute that VM image to people and offer a bounty to anyone who can breach it. Start over, do that again. Repeat. Once you feel confident with what you have, bring in a pro and see if they agree. Test some more... etc.
Rushing into this is sure to end in tears for you and, more importantly, your users, every time. There's nothing more dangerous than a cocky young web app developer who has absolutely no idea what they're getting into, and is playing with peoples' money.