I have an existing c# service running on a Windows client or server. To handle these I have added a simple http based management code, in order to install, remove, start and stop child processes (as services) remotely.
It works, however this management access needs some sort of authentication, else anyone knowing the system can screw it up pretty badly. As it is C#, I was thinking of using NTLM, hoping it was a built in set of libraries in the C#/.NET framework.
I can find plenty of examples on how to connect to an NTLM authenticated page/site, but not how to implement this myself on the server side.
Personally I would use WCF with a net.tcp binding to expose a management API from a Windows Service to Windows clients. net.tcp uses Windows authentication and encrypts the message out of the box.