I'm deploying my application on RackSpace and I have certain backend services (databases and such) that I need to ensure can't be accessed from any servers other than the ones I need to have access.

My plan is to have a script that periodically checks a web address for a whitelist and then uses that to dictate which IP addresses can access it's services.

There doesn't appear to be a simple tool that would allow me to do this.

If someone has experience in achieving this sort of security then please let me know how I can go about it.