Follow these instructions to implement or harden your virtual server
i am in the same boat. i am deploying onto vultr with these tips
https://www.vultr.com/docs/initial-secure-server-configuration-of-ubuntu-18-04
https://www.vultr.com/docs/category/security/
https://www.vultr.com/docs/vultr-firewall
many more to follow up on
This is how denial of service implementation works
https://www.vultr.com/products/ddos-protection/
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