using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Text;
 
using System.Runtime.InteropServices; // DllImport
using System.Security.Principal; // WindowsImpersonationContext
using System.Security.Permissions; // PermissionSetAttribute
 
namespace loginwin
{
 
    class Program
    {
 
         enum SECURITY_IMPERSONATION_LEVEL
        {
            SecurityAnonymous,
            SecurityIdentification,
            SecurityImpersonation,
            SecurityDelegation
        }
        [DllImport("ADVAPI32.DLL")]
        public static extern bool LogonUser(String lpszUsername, String lpszDomain, String lpszPassword,
                                            int dwLogonType, int dwLogonProvider, out IntPtr phToken);
        [DllImport("ADVAPI32.DLL")]
        public extern static bool DuplicateToken(IntPtr ExistingTokenHandle, int
                                                SECURITY_IMPERSONATION_LEVEL, out IntPtr DuplicateTokenHandle);
        [DllImport("kernel32.DLL")]
        static extern bool CloseHandle(IntPtr hObject);
 
 
        public static WindowsImpersonationContext  ImpersonateUser(string sUsername, string sDomain, string sPassword)
        {
            // initialize tokens
            IntPtr pExistingTokenHandle = new IntPtr(0);
            IntPtr pDuplicateTokenHandle = new IntPtr(0);
            pExistingTokenHandle = IntPtr.Zero;
            pDuplicateTokenHandle = IntPtr.Zero;
 
            // if domain name was blank, assume local machine
            if (sDomain == "")
                sDomain = System.Environment.MachineName;
 
            try
            {
                string sResult = null;
 
                const int LOGON32_PROVIDER_DEFAULT = 0;
                // create token
                const int LOGON32_LOGON_INTERACTIVE = 2;
                //const int SecurityImpersonation = 2;
                // get handle to token
                bool bImpersonated = LogonUser(sUsername, sDomain, sPassword,LOGON32_LOGON_INTERACTIVE, LOGON32_PROVIDER_DEFAULT,out pExistingTokenHandle);
 
                // did impersonation fail?
                if (false == bImpersonated)
                {
                    int nErrorCode = Marshal.GetLastWin32Error();
                    sResult = "LogonUser() failed with error code: " +
                        nErrorCode + "\r\n";
 
                    // show the reason why LogonUser failed
                    Console.WriteLine(sResult + "Error");
 
                }
 
                // Get identity before impersonation
                sResult += "Before impersonation: " +
                    WindowsIdentity.GetCurrent().Name + "\r\n";
 
                bool bRetVal = DuplicateToken(pExistingTokenHandle,
                    (int)SECURITY_IMPERSONATION_LEVEL.SecurityImpersonation,
                        out pDuplicateTokenHandle);
 
                // did DuplicateToken fail?
                if (false == bRetVal)
                {
                    int nErrorCode = Marshal.GetLastWin32Error();
                    // close existing handle
                    CloseHandle(pExistingTokenHandle);
                    sResult += "DuplicateToken() failed with error code: "
                        + nErrorCode + "\r\n";
 
                    // show the reason why DuplicateToken failed
                    Console.WriteLine(sResult+ "Error");
 
                    return null;
                }
                else
                {
                    // create new identity using new primary token
                    WindowsIdentity newId = new WindowsIdentity
                                                (pDuplicateTokenHandle);
                    WindowsImpersonationContext impersonatedUser =
                                                newId.Impersonate();
 
                    // check the identity after impersonation
                    sResult += "After impersonation: " +
                        WindowsIdentity.GetCurrent().Name + "\r\n";
 
                    Console.WriteLine(sResult+"Success");
                    return impersonatedUser;
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                // close handle(s)
                if (pExistingTokenHandle != IntPtr.Zero)
                    CloseHandle(pExistingTokenHandle);
                if (pDuplicateTokenHandle != IntPtr.Zero)
                    CloseHandle(pDuplicateTokenHandle);
 
 
            }
        }
        static void Main(string[] args)
        {
            ImpersonateUser("Username", System.Environment.MachineName.ToString(), "Password");
            Console.Read();
        }
}