I have my app (a PHP forum) and database on separate servers, and want to make sure that the connection between them is secure. I've taken all the preliminary steps that I've come to know of, and am wondering if I should secure the connection through SSH Tunneling or OpenVPN.
The problem is that, I am told, SSH Tunnel and OpenVPN can hog performance, especially when the app is write heavy (i.e. lots of data is constantly transferred to and from the database).
What I would like to know is, in the real world, do people connect app and database servers using SSH or OpenVPN, or do they consider it unnecessary, or are there any alternatives?
EDIT (1): The app and database servers are connected via the private network provided by my hosting service provider, but I hear that for anyone else (think a hacker) on the private network (i.e. other customers like me) it's just like a public IP address.