using System;
using System.Runtime.InteropServices;
using System.Security.Principal;

/// <summary>
/// Summary description for ThreadImpersonate
/// </summary>
public class ThreadImpersonate
{
    public const int LOGON32_LOGON_INTERACTIVE = 2;
    public const int LOGON32_PROVIDER_DEFAULT = 0;

WindowsImpersonationContext impersonationContext;

[DllImport("advapi32.dll")]
    public static extern int LogonUserA(String lpszUserName,
        String lpszDomain,
        String lpszPassword,
        int dwLogonType,
        int dwLogonProvider,
        ref IntPtr phToken);
    [DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern int DuplicateToken(IntPtr hToken,
        int impersonationLevel,
        ref IntPtr hNewToken);

[DllImport("advapi32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern bool RevertToSelf();

[DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    public static extern bool CloseHandle(IntPtr handle);

public bool ImpersonateValidUser(String userName, String domain, String password)
    {
        WindowsIdentity tempWindowsIdentity;
        IntPtr token = IntPtr.Zero;
        IntPtr tokenDuplicate = IntPtr.Zero;

if (RevertToSelf())
        {
            if (LogonUserA(userName, domain, password, LOGON32_LOGON_INTERACTIVE,
                LOGON32_PROVIDER_DEFAULT, ref token) != 0)
            {
                if (DuplicateToken(token, 2, ref tokenDuplicate) != 0)
                {
                    tempWindowsIdentity = new WindowsIdentity(tokenDuplicate);
                    impersonationContext = tempWindowsIdentity.Impersonate();
                    if (impersonationContext != null)
                    {
                        CloseHandle(token);
                        CloseHandle(tokenDuplicate);
                        return true;
                    }
                }
            }
        }
        if (token != IntPtr.Zero)
            CloseHandle(token);
        if (tokenDuplicate != IntPtr.Zero)
            CloseHandle(tokenDuplicate);
        return false;
    }

public void UndoImpersonation()
    {
        impersonationContext.Undo();

        protected void Page_Load(object sender, EventArgs e)
        {
            Thread.CurrentThread.Name = "Main Thread";
            ThreadIdentity();

for (int i = 0; i < 5; i++)
            {
                Thread t = new Thread(new ThreadStart(ThreadIdentity));
                t.Name = string.Format("Thread{0}", i + 1);
                t.Start();
            }
        }

protected void ThreadIdentity()
        {
            ThreadImpersonate impersonateMgr = new ThreadImpersonate();

string threadName = Thread.CurrentThread.Name;
            string identityName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
            if (impersonateMgr.ImpersonateValidUser("test1", string.Empty, "test"))
            {
                 threadName = Thread.CurrentThread.Name;
                 identityName = System.Security.Principal.WindowsIdentity.GetCurrent().Name;
                // Do Something in your code...
                impersonateMgr.UndoImpersonation();
            }