How to set up Ubuntu Server security?

Question

ubuntu

I found an article about the GUFW firewall, installed it, but when I tried to start it, I immediately received a warning that enabling it could disrupt existing SSH connections (I'm connected to the VPS via SSH, so I didn't do it) I would be grateful for the quality material on setting up security and administering the server on Ubuntu .
ufw enable

Answer 1

I completely agree with nexthop.
If you want to try it, do it on the machine to which you have physical access (you can wind up in such a way that you yourself can’t log in later)
Once you make your iptables config and you will pull it across all machines with minor changes.
I think that iptables is the most normal firewall.