We have a remote web server that talks to a SQL Server database (located in a different city) via a VPN. That's working fine. The SQL database is on 192.168.1.xxx on the local LAN, and in addition to those remote web apps, many local desktop applications also talk to it over the LAN.
After some bad weather brought large trees down and cut electric power for the better part of a week, management has asked me to move the SQL database off the LAN and up to the remote server, which is housed in a fancy datacenter with backup generators.
So I have all of these desktop applications that would need to go out over a new VPN to reach the remote SQL database.
The remote web server has a hardware firewall with only three ports opened to the world at present, port 80, a port for mail, and a port for Remote Desktop Connection.
Is there a way to set up a VPN so that the desktop applications here on the LAN can see the database up there on the remote server, the web apps on the remote server can see the database on the same remote server, but the port that SQL Server is listening on is not opened to the world in the firewall, while still using TCP as the SQL Server protocol?