What security settings should be made for the Ubuntu server?

Question

SSH

I created a droplet on Digital Ocean, installed Ubuntu 14.04, created a new user in the sudo group, denied root access via shh, changed the shh port, and I don’t know what to do next.
I plan to use the droplet for mastering nodejs and administration, so I would like to know what needs to be done to secure my server as much as possible or is everything already out of the box in order?

Answer 1

maximum - deny all in iptables for all addresses, allow for your external ip. And yes, non-standard apache, mysql, etc ports

Answer 2

They also have great articles:
https://www.digitalocean.com/community/tutorials/i...
https://www.digitalocean.com/community/tutorials/a...