Try this:
using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;
namespace EnumerateRDUsers
{
class Program
{
[DllImport("wtsapi32.dll")]
static extern IntPtr WTSOpenServer([MarshalAs(UnmanagedType.LPStr)] String pServerName);
[DllImport("wtsapi32.dll")]
static extern void WTSCloseServer(IntPtr hServer);
[DllImport("wtsapi32.dll")]
static extern Int32 WTSEnumerateSessions(
IntPtr hServer,
[MarshalAs(UnmanagedType.U4)] Int32 Reserved,
[MarshalAs(UnmanagedType.U4)] Int32 Version,
ref IntPtr ppSessionInfo,
[MarshalAs(UnmanagedType.U4)] ref Int32 pCount);
[DllImport("wtsapi32.dll")]
static extern void WTSFreeMemory(IntPtr pMemory);
[DllImport("Wtsapi32.dll")]
static extern bool WTSQuerySessionInformation(
System.IntPtr hServer, int sessionId, WTS_INFO_CLASS wtsInfoClass, out System.IntPtr ppBuffer, out uint pBytesReturned);
[StructLayout(LayoutKind.Sequential)]
private struct WTS_SESSION_INFO
{
public Int32 SessionID;
[MarshalAs(UnmanagedType.LPStr)]
public String pWinStationName;
public WTS_CONNECTSTATE_CLASS State;
}
public enum WTS_INFO_CLASS
{
WTSInitialProgram,
WTSApplicationName,
WTSWorkingDirectory,
WTSOEMId,
WTSSessionId,
WTSUserName,
WTSWinStationName,
WTSDomainName,
WTSConnectState,
WTSClientBuildNumber,
WTSClientName,
WTSClientDirectory,
WTSClientProductId,
WTSClientHardwareId,
WTSClientAddress,
WTSClientDisplay,
WTSClientProtocolType
}
public enum WTS_CONNECTSTATE_CLASS
{
WTSActive,
WTSConnected,
WTSConnectQuery,
WTSShadow,
WTSDisconnected,
WTSIdle,
WTSListen,
WTSReset,
WTSDown,
WTSInit
}
static void Main(string[] args)
{
ListUsers("<insert servername="" here="">");
}
public static IntPtr OpenServer(String Name)
{
IntPtr server = WTSOpenServer(Name);
return server;
}
public static void CloseServer(IntPtr ServerHandle)
{
WTSCloseServer(ServerHandle);
}
public static void ListUsers(String ServerName)
{
IntPtr serverHandle = IntPtr.Zero;
List<string> resultList = new List<string>();
serverHandle = OpenServer(ServerName);
try
{
IntPtr SessionInfoPtr = IntPtr.Zero;
IntPtr userPtr = IntPtr.Zero;
IntPtr domainPtr = IntPtr.Zero;
Int32 sessionCount = 0;
Int32 retVal = WTSEnumerateSessions(serverHandle, 0, 1, ref SessionInfoPtr, ref sessionCount);
Int32 dataSize = Marshal.SizeOf(typeof(WTS_SESSION_INFO));
Int32 currentSession = (int)SessionInfoPtr;
uint bytes = 0;
if (retVal != 0)
{
for (int i = 0; i < sessionCount; i++)
{
WTS_SESSION_INFO si = (WTS_SESSION_INFO)Marshal.PtrToStructure((System.IntPtr)currentSession, typeof(WTS_SESSION_INFO));
currentSession += dataSize;
WTSQuerySessionInformation(serverHandle, si.SessionID, WTS_INFO_CLASS.WTSUserName, out userPtr, out bytes);
WTSQuerySessionInformation(serverHandle, si.SessionID, WTS_INFO_CLASS.WTSDomainName, out domainPtr, out bytes);
Console.WriteLine("Domain and User: " + Marshal.PtrToStringAnsi(domainPtr) + "\\" + Marshal.PtrToStringAnsi(userPtr));
}
WTSFreeMemory(SessionInfoPtr);
}
}
finally
{
CloseServer(serverHandle);
}
}
}
}</string></string></insert>
Ref: stackoverflow.com