public class IdentityScope : IDisposable
{
    // obtains user token
    [DllImport("advapi32.dll", SetLastError = true)]
    static extern bool LogonUser(string pszUsername, string pszDomain, string pszPassword,int dwLogonType, int dwLogonProvider, ref IntPtr phToken);
    // closes open handes returned by LogonUser
    [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
    extern static bool CloseHandle(IntPtr handle);

    [DllImport("Advapi32.DLL")]
    static extern bool ImpersonateLoggedOnUser(IntPtr hToken);
    [DllImport("Advapi32.DLL")]
    static extern bool RevertToSelf();
    const int LOGON32_PROVIDER_DEFAULT = 0;
    const int LOGON32_LOGON_NEWCREDENTIALS = 9;//域ò控?中D的?需è要a用?:Interactive = 2
    private bool disposed;
    /// <summary>
    /// 登?錄?
    /// </summary>
    /// <param name="sUsername">用?戶§名?</param>
    /// <param name="sDomain">域ò名?，?如?果?不?在ú域ò中D就í使1用?機(jī)ú器÷IP地?址·</param>
    /// <param name="sPassword">密ü碼?</param>
    public IdentityScope(string sUsername, string sDomain, string sPassword)
    {
      // initialize tokens
      IntPtr pExistingTokenHandle = new IntPtr(0);
      IntPtr pDuplicateTokenHandle = new IntPtr(0);
      try
      {
        // get handle to token
        bool bImpersonated = LogonUser(sUsername, sDomain, sPassword,LOGON32_LOGON_NEWCREDENTIALS, LOGON32_PROVIDER_DEFAULT, ref pExistingTokenHandle);
        if (true == bImpersonated)
        {
          if (!ImpersonateLoggedOnUser(pExistingTokenHandle))
          {
            int nErrorCode = Marshal.GetLastWin32Error();
            throw new Exception("ImpersonateLoggedOnUser error;Code=" + nErrorCode);
          }
        }
        else
        {
          int nErrorCode = Marshal.GetLastWin32Error();
          throw new Exception("LogonUser error;Code=" + nErrorCode);
        }
      }
      finally
      {
        // close handle(s)
        if (pExistingTokenHandle != IntPtr.Zero)
          CloseHandle(pExistingTokenHandle);
        if (pDuplicateTokenHandle != IntPtr.Zero)
          CloseHandle(pDuplicateTokenHandle);
      }
    }
    protected virtual void Dispose(bool disposing)
    {
      if (!disposed)
      {
        RevertToSelf();
        disposed = true;
      }
    }
    public void Dispose()
    {
      Dispose(true);
    }
  }

using (IdentityScope c = new IdentityScope("administrator", "192.168.0.1", "11111"))
{
 string[] filelist = System.IO.Directory.GetDirectories(@"\\192.168.0.1\folderName");
}