How to pass credentials during writing file at ser

Question

I would like to write a file at server path but when I tried to do that we got exception that we have no permission to do that. We have an application ID and password who has permission to write at the server path but I do not know how can I pass this credentials :

My current code :

//Create a new GUID, extract the extension and create a new unique filename
string strFileGUID = System.Guid.NewGuid().ToString();
string extension = Path.GetExtension(attachment.AttachmentFileName);
string tempfilename = strFileGUID  + extension;  

string path = "ServerPath";

//Open a filestream and write the contents of the file at server path
FileStream fs = new FileStream(path, FileMode.Create, FileAccess.Write );
fs.Write(fileContent.Content, 0, fileContent.Content.Length);
fs.Flush();
fs.Close();

Answer 1

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

Example:

IntPtr userToken = IntPtr.Zero;

bool success = External.LogonUser(
  "john.doe", 
  "domain.com", 
  "MyPassword", 
  (int) AdvApi32Utility.LogonType.LOGON32_LOGON_INTERACTIVE, //2
  (int) AdvApi32Utility.LogonProvider.LOGON32_PROVIDER_DEFAULT, //0
  out userToken);

if (!success)
{
  throw new SecurityException("Logon user failed");
}

using (WindowsIdentity.Impersonate(userToken))
{
  // put your code here
}