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)
}

Solution

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;
    }
}