On trying to make a Remote Desktop connection from a Windows 7 PC to another Windows 7 PC I received the following error:
Remote Desktop Connection An authentication error has occurred. The Local Security Authority cannot be contacted Remote computer: <computername>
Additionally, the following error was logged in the System event log:
Log Name: System Source: TermDD Event ID: 56 Level: Error Description: The Terminal Server security layer detected an error in the protocol stream and has disconnected the client. Client IP: aaa.bbb.ccc.ddd.
Clicking the Details tab, you can see the following:
Binary data: In Words 0000: 00040000 002C0002 00000000 C00A0038 0008: 00000000 C00A0038 00000000 00000000 0010: 00000000 00000000 C0000070
The last word in my case is C0000070. This is the error code in hexadecimal. Using the err.exe error code lookup tool (which despite what the download page says, is not just for Exchange) gave me the following information:
# for hex 0xc0000070 / decimal -1073741712 : STATUS_INVALID_WORKSTATION ntstatus.h # The user account is restricted such that it may not be used # to log on from the source workstation. # 1 matches found for "C0000070"
Which is both helpful and interesting, and enabled me to solve the problem. The PC I was trying to make the RDP connection to was running some “server” software that ran as a desktop application, not as a service. Thus the PC had to be permanently logged on with a particular account. In order to stop this account from being used to log on to other PCs I had configured it’s properties in Active Directory such that it was only allowed to log on to one computer name. It seems as though this also blocks you from being able to make Remote Desktop connections using that account from other PCs – even if you’re trying to connect to the allowed PC. So I had to take the restriction off the user account, once that was done Remote Desktop worked normally.