What is the best way to connect a website on a VPS to sql server 2008 R2 express, using MDF files as databases. The VPS is running on server 2008 R2. I installed the same environment on the development computer. IIS gets a connection because it sees the users that are in the ASPNETDB.MDF file. (Beside that I have another database.) But as soon as I run the website and try to log in, the application crashes. I tried using integrated security and user instance in the connectionstring in the webconfig file, but get the error that the user instance could not be created. I made a user in sql server but that user can only be linked to existing databases (so MASTER) and when logging in to the website i get the error that ASPNETDB.MDF could not be created in the MASTER database because that file already exist (so this would be completely wrong). So how can I connect it in the right way? I would rather keep on using MDF files in the App_Data directory of the website, but is that a good thing? Is it secure on the VPS?