Identify if a server is currently accessed via Remote Desktop Connection
Solution 1:
This applies to the following OS: Windows Server 2008, Windows Server 2008 R2, Windows Server 2012 and Windows Vista. Try this command:
query session [<SessionName> | <UserName> | <SessionID>] [/server:<ServerName>] [/mode] [/flow] [/connect] [/counter]
This should give output like the following:
C:\>query session
SESSIONNAME USERNAME ID STATE TYPE DEVICE
>console Administrator1 0 active wdcon
rdp-tcp#1 User1 1 active wdtshare
rdp-tcp 2 listen wdtshare
4 idle
5 idle
Source
Hope this helps.