Required Security,Linux System Administration freelancer for Secure Linux(centos 8) server Digital ocean job

My site is already running on centos 8 digital ocean droplet. I have used Tomcat 9 (as an application server) and I do have an apache web server on the front.

Previously on my ubuntu droplet got a malware attack(maybe kinsing). so I have created a new droplet with the centos and destroyed the old. So this time I want to make sure my current server 100% secure from any kind of attack.

Your task would be:
1) Secure Linux server
2) appropriate permissions
3) Secure Apache webserver(prevention from ddos attack)
4) you can suggest any better options available

Skills & Expertise Required

Security Linux System Administration