仅当在web.config中指定用户时，ASP.NET模拟才起作用

Question

First, I apologize is this a duplicate, but I really couldn't find a similar problem anywhere.

The situation is I'm attempting to use the impersonation feature in asp.net to retrieve a file located on a network directory. When I specify the user in the web.config, it works fine:

<identity impersonate="true" userName="contoso\Jane" password="********" />

However, when I try using the following, I recieve a prompt to login to the site, which I'm never able to do successfully.

<identity impersonate="true"/>

My understanding of the latter example is that it will attempt to impersonate with the windows credential of whomever is currently viewing the page (via windows authentication). Is this not correct?

I should note, I do have windows authentication working properly in other areas of the app.

Thanks

EDIT

I should also mention, this is running on II6... and it just "feels" like a configuration issue...

Answer 1

I would go a other way with a extra class Impersonate.cs and You need a user, a password and a Domain.

Imperosnate.cs :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web.Security;
using System.Security.Principal;
using System.Runtime.InteropServices;
using System.IO;
using System.Text;

using System.Web;

namespace [YourProgramName]  //You must change it
{
    public class Impersonate
    {

        [DllImport("advapi32.dll", SetLastError = true)]
        private static extern int LogonUser(string lpszUsername, string lpszDomain, string lpszPassword,
                                            int dwLogonType, int dwLogonProvider, out int phToken);

        [DllImport("kernel32.dll")]
        private static extern int FormatMessage(int dwFlags, string lpSource, int dwMessageId, int dwLanguageId,
                                                StringBuilder lpBuffer, int nSize, string[] Arguments);


        private const int LOGON32_LOGON_NETWORK_CLEARTEXT = 8;
        private const int LOGON32_PROVIDER_DEFAULT = 0;
        private const int FORMAT_MESSAGE_FROM_SYSTEM = 0x1000;

        private static WindowsImpersonationContext winImpersonationContext = null;

        public static void ImpersonateUser(string domain, string userName, string password)
        {

            //Benutzer einloggen
            int userToken = 0;

            bool loggedOn = (LogonUser(userName, domain, password, LOGON32_LOGON_NETWORK_CLEARTEXT,
                                        LOGON32_PROVIDER_DEFAULT, out userToken) != 0);

            if (loggedOn == false)
            {
                int apiError = Marshal.GetLastWin32Error();
                StringBuilder errorMessage = new StringBuilder(1024);
                FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM, null, apiError, 0, errorMessage, 1024, null);
                throw new Exception(errorMessage.ToString());
            }

            WindowsIdentity identity = new WindowsIdentity((IntPtr)userToken);
            winImpersonationContext = identity.Impersonate();

        }

        public static void UndoImpersonation()
        {
            if (winImpersonationContext != null)
            {
                winImpersonationContext.Undo();
            }
        }

    }
}

Use it in your program:

string Admin = Properties.Settings.Default.Admin;
        string AdminPassword = Properties.Settings.Default.AdminPassword;
        string Domain = Properties.Settings.Default.Domain;

        Impersonate.ImpersonateUser(Domain , Admin , AdminPassword);

                                //Your Code as the new User


                      Impersonate.UndoImpersonation();

hope it is what you search ^^