I've set authentication level:i:0 in the RDP file, but when I connect to this computer with mstsc it asks me if I want to connect to this computer, so the parameter is ignored by the mstsc. How to fix it?
Just as I suspected, it's a publisher warning. Auth level won't help that, but there's a couple of things you can do.
1) Sign the RDP shortcut. This involves digitally signing the shortcut with a certificate that is trusted in your environment. This was a bit too involved for me to do in my environment, but there's enought info online for it to be done. There's an exe that comes with the server OSes that's called
rdpsign, and you use that to sign the rdp file.
2)Checking that checkbox will insert a reg key onto the computer to let it know that rdp connections to that computer are okay, so it doesn't prompt again. You could add the reg key to your clients via group policy, or whatever you prefer. I forget where it writes, this question addresses it partially, but I have a feeling it writes to other reg keys also, b/c there is a key that stores the fqdn. It should be trivial to find with procmon.