I'm looking to set up a VPN server and I'm trying to figure out what software to use. My problem is that I have no idea what the term for the arrangement I want is so I can't really google for it. What I want is to have a "virtual" LAN where the only access is by VPN, where having access to the VPN only give you access to other VPN clients; not to the general internet, and not to the server running the VPN.
My primary use case is getting uniform access between clients I own where one or both may be behind a NAT and/or firewall that may not have a consistent IP.
(p.s. Given my budget I'll have to stick with freeware/FOSS.)
Edit: The VPN server is not in the same NAT/Firewall/IP situation. It's able to serve up whatever I want from a static IP.