CloudLinux is an amazing thing.
I have used it while I owned two hosting companies.
And I had over 1000 clients, it keeps server from overloading, and from hacker attacks.
With cloud linux every user can have its own resources, like very very small vps.
Also, it keeps an user account for breaking in another.
Like symlink race condition protection!
Cloudlinux costs only 14$
In addition, i highly recommend using KernelCare.
Its amazing piece of software, it updates kernel with latest security patches without needing rebooting machine.
This means you can have really big uptime.
And it costs only $3.95!
Believe me, if you are serious about your job with server you need to have these two software.
I hope you guys will tell me your experiences bellow in comments.