How to impersonate not local user?

Question

Hi, I ask you for a problem I can't resolve.
I'm developing a form application in C# and I need to access a web application (IIS) within the intranet and not to insert crediantials manually (I keep them in code).
I tried using both Win32NativeMethods.LogonUser and advapi32.dll's Logon User methods, but they both return false. Why? Username, domain and password I use are profiled on the remote machine, not on my local machine. Might this be the problem?
There are some solutions on the web but they don't work for me.
Could you help me, please?
Following is the code I tried to use (references: http://platinumdogs.wordpress.com/2008/10/30/net-c-impersonation-with-network-credentials/#comment-770)

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.IO;
using System.Security.Principal;
using System.Runtime.InteropServices;
using System.ComponentModel;
namespace OpenWebBrowser_authenticated_CS
{
class Program
{
[STAThread]
static void Main(string[] args)
{
using (new Impersonator("username", "domain", "password"))
{
string siteUrl = "http://myremotewebapplication"; 
System.Diagnostics.Process.Start(siteUrl);
}
}
}
public enum LogonType
{
LOGON32_LOGON_INTERACTIVE = 2,
LOGON32_LOGON_NETWORK = 3,
LOGON32_LOGON_BATCH = 4,
LOGON32_LOGON_SERVICE = 5,
LOGON32_LOGON_UNLOCK = 7,
LOGON32_LOGON_NETWORK_CLEARTEXT = 8, // Win2K or higher
LOGON32_LOGON_NEW_CREDENTIALS = 9 // Win2K or higher
};
public enum LogonProvider
{
LOGON32_PROVIDER_DEFAULT = 0,
LOGON32_PROVIDER_WINNT35 = 1,
LOGON32_PROVIDER_WINNT40 = 2,
LOGON32_PROVIDER_WINNT50 = 3
};
public enum ImpersonationLevel
{
SecurityAnonymous = 0,
SecurityIdentification = 1,
SecurityImpersonation = 2,
SecurityDelegation = 3
}
class Win32NativeMethods
{
[DllImport("advapi32.dll", SetLastError = true)]
public static extern int LogonUser(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);
}
/// <summary>
/// Allows code to be executed under the security context of a specified user account.
/// </summary>
/// <remarks> 
///
/// Implements IDispose, so can be used via a using-directive or method calls;
/// ...
///
/// var imp = new Impersonator( "myUsername", "myDomainname", "myPassword" );
/// imp.UndoImpersonation();
///
/// ...
///
/// var imp = new Impersonator();
/// imp.Impersonate("myUsername", "myDomainname", "myPassword");
/// imp.UndoImpersonation();
///
/// ...
///
/// using ( new Impersonator( "myUsername", "myDomainname", "myPassword" ) )
/// {
/// ...
/// [code that executes under the new context]
/// ...
/// }
///
/// ...
/// </remarks>
public class Impersonator : IDisposable
{
private WindowsImpersonationContext _wic;
/// <summary>
/// Begins impersonation with the given credentials, Logon type and Logon provider.
/// </summary>
///<param name="userName">Name of the user.</param>
///<param name="domainName">Name of the domain.</param>
///<param name="password">The password. <see cref="System.String"/></param>
///<param name="logonType">Type of the logon.</param>
///<param name="logonProvider">The logon provider. <see cref="Mit.Sharepoint.WebParts.EventLogQuery.Network.LogonProvider"/></param>
public Impersonator(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
{
Impersonate(userName, domainName, password, logonType, logonProvider);
}
/// <summary>
/// Begins impersonation with the given credentials.
/// </summary>
///<param name="userName">Name of the user.</param>
///<param name="domainName">Name of the domain.</param>
///<param name="password">The password. <see cref="System.String"/></param>
public Impersonator(string userName, string domainName, string password)
{
Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
}
/// <summary>
/// Initializes a new instance of the <see cref="Impersonator"/> class.
/// </summary>
public Impersonator()
{ }
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose()
{
UndoImpersonation();
}
/// <summary>
/// Impersonates the specified user account.
/// </summary>
///<param name="userName">Name of the user.</param>
///<param name="domainName">Name of the domain.</param>
///<param name="password">The password. <see cref="System.String"/></param>
public void Impersonate(string userName, string domainName, string password)
{
Impersonate(userName, domainName, password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT);
}
/// <summary>
/// Impersonates the specified user account.
/// </summary>
///<param name="userName">Name of the user.</param>
///<param name="domainName">Name of the domain.</param>
///<param name="password">The password. <see cref="System.String"/></param>
///<param name="logonType">Type of the logon.</param>
///<param name="logonProvider">The logon provider. <see cref="Mit.Sharepoint.WebParts.EventLogQuery.Network.LogonProvider"/></param>
public void Impersonate(string userName, string domainName, string password, LogonType logonType, LogonProvider logonProvider)
{
UndoImpersonation();
IntPtr logonToken = IntPtr.Zero;
IntPtr logonTokenDuplicate = IntPtr.Zero;
try
{
// revert to the application pool identity, saving the identity of the current requestor
_wic = WindowsIdentity.Impersonate(IntPtr.Zero);
// do logon & impersonate
if (Win32NativeMethods.LogonUser(userName,
domainName,
password,
(int)logonType,
(int)logonProvider,
ref logonToken) != 0)
{
if (Win32NativeMethods.DuplicateToken(logonToken, (int)ImpersonationLevel.SecurityImpersonation, ref logonTokenDuplicate) != 0)
{
WindowsIdentity wi = new WindowsIdentity(logonTokenDuplicate);
wi.Impersonate(); // discard the returned identity context (which is the context of the application pool)
}
else
throw new Win32Exception(Marshal.GetLastWin32Error());
}
else
throw new Win32Exception(Marshal.GetLastWin32Error());
}
finally
{
if (logonToken != IntPtr.Zero)
Win32NativeMethods.CloseHandle(logonToken);
if (logonTokenDuplicate != IntPtr.Zero)
Win32NativeMethods.CloseHandle(logonTokenDuplicate);
}
}
/// <summary>
/// Stops impersonation.
/// </summary>
private void UndoImpersonation()
{
// restore saved requestor identity
if (_wic != null)
_wic.Undo();
_wic = null;
}
}
}