C# Get RDC/RDP and "Console" Session information

Question

I'm trying to retrieve some RDC/RDP and "Console" login information programmatically via C#.

I want to develop a simple console application (.EXE) such that I can retreive the information from Task Manager -> Users Tab of any remote computer on our domain (Windows Server 2003 x86, or 2008R2 x64).

This shows if a person is logged onto the server directly (i.e. the Console) or over RDC/RDP (including the client if it is still active) or disconnected if it is "suspended" (i.e. they have not logged off but just closed the RDC/RDP windows temporarily)

I have admin permissions on all servers and can configure any windows services/firewalls rules that need to be enabled/disabled (if required)

I think I have to probably use WMI (using System.Management) but the examples I have found from google only retrieve the existing user.

//Method 1
var searcher = new ManagementObjectSearcher(
               "SELECT UserName FROM Win32_ComputerSystem");
var collection = Searcher.Get();
foreach(ManagementObject entry in collection)
{
  Console.WriteLine(entry["UserName"]);
}

//Method 2
string computer = "somecomputername";   
var searcher = new ManagementObjectSearcher(
               computer + @"root\CIMV2", "SELECT * FROM Win32_TerminalService");
var collection = Searcher.Get();
foreach(ManagementObject entry in collection)
{
  //Write them out (although usernames isnt listed from the example I found)
}

Answer 1

This will give you everything you need. Just call ListSessions and pass in the server name. To get additional session information, pass the ServerName and SessionId to GetSessionInfo.

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace TerminalTools
{
    public class TermServicesManager
    {

        [DllImport("wtsapi32.dll")]
        static extern IntPtr WTSOpenServer([MarshalAs(UnmanagedType.LPStr)] String pServerName);

        [DllImport("wtsapi32.dll")]
        static extern void WTSCloseServer(IntPtr hServer);

        [DllImport("Wtsapi32.dll")]
        public static extern bool WTSQuerySessionInformation(IntPtr hServer, int sessionId, WTS_INFO_CLASS wtsInfoClass,
            out System.IntPtr ppBuffer, out uint pBytesReturned);

        [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);

        [StructLayout(LayoutKind.Sequential)]
        private struct WTS_SESSION_INFO
        {
            public Int32 SessionID;
            [MarshalAs(UnmanagedType.LPStr)]
            public String pWinStationName;
            public WTS_CONNECTSTATE_CLASS State;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct WTS_CLIENT_ADDRESS
        {
            public uint AddressFamily;
            [MarshalAs(UnmanagedType.ByValArray, SizeConst = 20)]
            public byte[] Address;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct WTS_CLIENT_DISPLAY
        {
            public uint HorizontalResolution;
            public uint VerticalResolution;
            public uint ColorDepth;
        }

        public enum WTS_CONNECTSTATE_CLASS
        {
            Active,
            Connected,
            ConnectQuery,
            Shadow,
            Disconnected,
            Idle,
            Listen,
            Reset,
            Down,
            Init
        }

        public enum WTS_INFO_CLASS
        {
            InitialProgram = 0,
            ApplicationName = 1,
            WorkingDirectory = 2,
            OEMId = 3,
            SessionId = 4,
            UserName = 5,
            WinStationName = 6,
            DomainName = 7,
            ConnectState = 8,
            ClientBuildNumber = 9,
            ClientName = 10,
            ClientDirectory = 11,
            ClientProductId = 12,
            ClientHardwareId = 13,
            ClientAddress = 14,
            ClientDisplay = 15,
            ClientProtocolType = 16
        }

                        private static IntPtr OpenServer(string Name)
    {
        IntPtr server = WTSOpenServer(Name);
        return server;
    }

                    private static void CloseServer(IntPtr ServerHandle)
    {
        WTSCloseServer(ServerHandle);
    }

        public static List<TerminalSessionData> ListSessions(string ServerName)
        {
            IntPtr server = IntPtr.Zero;
            List<TerminalSessionData> ret = new List<TerminalSessionData>();
            server = OpenServer(ServerName);

            try
            {
                IntPtr ppSessionInfo = IntPtr.Zero;

                Int32 count = 0;
                Int32 retval = WTSEnumerateSessions(server, 0, 1, ref ppSessionInfo, ref count);
                Int32 dataSize = Marshal.SizeOf(typeof(WTS_SESSION_INFO));

                Int64 current = (int)ppSessionInfo;

                if (retval != 0)
                {
                    for (int i = 0; i < count; i++)
                    {
                        WTS_SESSION_INFO si = (WTS_SESSION_INFO)Marshal.PtrToStructure((System.IntPtr)current, typeof(WTS_SESSION_INFO));
                        current += dataSize;

                        ret.Add(new TerminalSessionData(si.SessionID, si.State, si.pWinStationName));
                    }

                    WTSFreeMemory(ppSessionInfo);
                }
            }
            finally
            {
                CloseServer(server);
            }

            return ret;
        }

        public static TerminalSessionInfo GetSessionInfo(string ServerName, int SessionId)
        {
            IntPtr server = IntPtr.Zero;
            server = OpenServer(ServerName);
            System.IntPtr buffer = IntPtr.Zero;
            uint bytesReturned;
            TerminalSessionInfo data = new TerminalSessionInfo();

            try
            {
                bool worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ApplicationName, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                string strData = Marshal.PtrToStringAnsi(buffer);
                data.ApplicationName = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientAddress, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                WTS_CLIENT_ADDRESS si = (WTS_CLIENT_ADDRESS)Marshal.PtrToStructure((System.IntPtr)buffer, typeof(WTS_CLIENT_ADDRESS));
                data.ClientAddress = si;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientBuildNumber, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                int lData = Marshal.ReadInt32(buffer);
                data.ClientBuildNumber = lData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientDirectory, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                strData = Marshal.PtrToStringAnsi(buffer);
                data.ClientDirectory = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientDisplay, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                WTS_CLIENT_DISPLAY cd = (WTS_CLIENT_DISPLAY)Marshal.PtrToStructure((System.IntPtr)buffer, typeof(WTS_CLIENT_DISPLAY));
                data.ClientDisplay = cd;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientHardwareId, out buffer, out bytesReturned);

                if (!worked)
                    return data;

                lData = Marshal.ReadInt32(buffer);
                data.ClientHardwareId = lData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientName, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.ClientName = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientProductId, out buffer, out bytesReturned);
                Int16 intData = Marshal.ReadInt16(buffer);
                data.ClientProductId = intData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ClientProtocolType, out buffer, out bytesReturned);
                intData = Marshal.ReadInt16(buffer);
                data.ClientProtocolType = intData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.ConnectState, out buffer, out bytesReturned);
                lData = Marshal.ReadInt32(buffer);
                data.ConnectState = (WTS_CONNECTSTATE_CLASS)Enum.ToObject(typeof(WTS_CONNECTSTATE_CLASS), lData);

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.DomainName, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.DomainName = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.InitialProgram, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.InitialProgram = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.OEMId, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.OEMId = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.SessionId, out buffer, out bytesReturned);
                lData = Marshal.ReadInt32(buffer);
                data.SessionId = lData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.UserName, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.UserName = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.WinStationName, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.WinStationName = strData;

                worked = WTSQuerySessionInformation(server, SessionId,
                    WTS_INFO_CLASS.WorkingDirectory, out buffer, out bytesReturned);
                strData = Marshal.PtrToStringAnsi(buffer);
                data.WorkingDirectory = strData;
            }
            finally
            {
                WTSFreeMemory(buffer);
                buffer = IntPtr.Zero;
                CloseServer(server);
            }

            return data;
        }

    }

    public class TerminalSessionData
    {
        public int SessionId;
        public TermServicesManager.WTS_CONNECTSTATE_CLASS ConnectionState;
        public string StationName;

                            public TerminalSessionData(int sessionId, TermServicesManager.WTS_CONNECTSTATE_CLASS connState, string stationName)
    {
        SessionId = sessionId;
        ConnectionState = connState;
        StationName = stationName;
    }

                    public override string ToString()
    {
        return String.Format("{0} {1} {2}", SessionId, ConnectionState, StationName);
    }
    }

    public class TerminalSessionInfo
    {
        public string InitialProgram;
        public string ApplicationName;
        public string WorkingDirectory;
        public string OEMId;
        public int SessionId;
        public string UserName;
        public string WinStationName;
        public string DomainName;
        public TermServicesManager.WTS_CONNECTSTATE_CLASS ConnectState;
        public int ClientBuildNumber;
        public string ClientName;
        public string ClientDirectory;
        public int ClientProductId;
        public int ClientHardwareId;
        public TermServicesManager.WTS_CLIENT_ADDRESS ClientAddress;
        public TermServicesManager.WTS_CLIENT_DISPLAY ClientDisplay;
        public int ClientProtocolType;
    }
}