And one simple mistake, and we're screwed
Once I changed the ssh port to a large number, the OOM and heavy CPU usage stopped, and never came back. So, I think I'm safe, though I keep an eye on the logs, and for any unknown processes, but never seen anything out of ordinary.
The 64gb machine is my dev machine, as my IDE(intellij) runs on high memory config and I run some heavy process, it could've been combined with the ssh spam it went OOM. I still run all the things, without any issues now.
There were like thousands of requests in an hour, and that went on continuously, before I changed the port.
But, on home computer, I do not want to be bothered with all the security efforts, and want to keep it simple. But I have plans to put up an isolated server setup someday. But too broke right now, and looking for a job. heh.
I have seen people, who is using simple password based authentication, with really simple password. I always go and fix that first, so, it's too common, which is why It's scary.
Works so well that it's easy to forget they're running.
Once I had Postgresql db with default password on a new vps, and forgetting to disable password based login, on a server with no domain. And it got hacked in a day, and was being used as bot server. And that was 10 years ago.
Recently deployed server, and was getting ssh login attempts within an hour, and it didn't had a domain. Fortunately, I've learned my lesson, and turned of password based login as soon as the server was up and running.
And similar attempts bogged down my desktop to halt.
Having an machine open to the world is now very scary. Thanks God for service like tailscale exists.