I use a DigitalOcean Ubuntu 16.04 machine with Bash, LEMP and WordPress.
I already did the best I can to protect the system and WordPress from BFAs and Backdoors, and to protect WordPress from DB injection by issuing only one simple contact form and automatic updates from the WP-CLI.
In all humbleness, it's unlikely that I'll be attacked in DDoS, but I do have a small fear of a single machine DoS (SMDoS) attack as many data requests from one machine.
The fear of an SMDoS woke up in my mind after thinking that I cannot know if someday I'll have a clash with some unstable person which happens to know Linux cracking well enough and will try to destroy a site / server environment I have I have as a revenge.
Gladly I didn't have to cope with such case but I do want to prepare myself for such unlikely case. SMDoS is indeed something just one human can do.