Not sure this is the right place to ask this but I'll give a shot.
I've been asked to implement a system about criminality data. The data is security sensitive, in that it contains information about crimes done by certain people in a violent context and delicate country.
Actually, the application will only have 4-5 users. Maybe a handful more later. Nevertheless they are distributed and thus there should be access over a network.
They currently run a Windows server. I am highly experienced in linux environments, my Windows server is quite dated.
What could be a good setup for such an application? If I installed it at their own premises, which seems to be their preferred approach, how would I go about providing access to the users? Is a VPN a good approach? Any relevant info about how to do this with Windows? Can I do it without having to host the app on the Internet? Other suggestions?
Not sure if a standard web application hosted on a server somewhere on the Internet could be sufficient.
I apologize if the question is too vague. I am happy to try to provide more information if I can. I am an experienced developer but not so much a system engineer.