If you're trying to be cost-effective, renting a VPS for a fixed term instead of using a IaaS platform that provides all these things just by clicking a checkbox, then caring about your firewall is a necessary part of building the system image that you deploy. You can of course set up your own private networking between systems and build the same type of architecture that a IaaS would provide, but to do that you're going to need to understand everything about linux networking and netfilter already.