We have a combination of a modem router with a plain Dell WinXP pc behind it on several locations in the field. They are unattended. We do however want to secure them from unauthorized access from the internet. Right now we run a VNC and FTP server on them.
The question is how we best secure those pc's. Are there ADSL annex A modem routers that can have their firewall's IP's/MAC address lists updated in some easy automatic way remotely, so we don't have to do this one by one?
Besides the router I was thinking along the lines of a software firewall to limit access to IP's or MAC addresses from our offices and employees. But if someone gets a new pc, how do you deal with this then? Connecting to each and every pc in the field to manually update it's firewall is not an option. Are there mechanisms to do this in an easier way? Cost is also an issue, so it doesn't have to be top of the line, millions of clients supporting software. Open source is welcome too!
Thank a lot for your advice!