FTP File Transfer

I am trying to access a FTP secured site (SSL/TSL) and transfer a file in VB.Net using FTPRequest. When I try to complete the transfer I get an error back "The remote certificate is invalid according to the validation procedure".

However when I connect to the same FTP site with FileZilla UI, I can transfer files with no problem. Why can do transfers with FileZilla and not in VB.Net? Does FileZilla have its own Certificate?

Can you show us the code you're using?

here is the code: I have replace the siteid, userid and password from the code.

Dim URI As String = "FTP://<ftpsite.com>"
Dim UserName As String = "<userid>"
Dim Password As String = "<userpsw>"

Dim WResp As FtpWebResponse
Dim Wreq As FtpWebRequest = DirectCast(FtpWebRequest.Create(URI & "/test.txt"), FtpWebRequest)
Try

Wreq.EnableSsl = True
Wreq.KeepAlive = True
Wreq.UsePassive = True

Wreq.Method = WebRequestMethods.Ftp.UploadFile
Wreq.Credentials = New System.Net.NetworkCredential(UserName, Password)
Dim bFile() As Byte = System.IO.File.ReadAllBytes("f:\ftpud.txt")

' upload file...
****** it is here when I try the GetRequestStream that I get the error *****
Dim clsStream As System.IO.Stream = Wreq.GetRequestStream()

clsStream.Write(bFile, 0, bFile.Length)
clsStream.Close()
clsStream.Dispose()
WResp = Wreq.GetResponse()

Catch ew As WebException
MsgBox(ew.Message)
Catch e As Exception
MsgBox(e.Message)
End Try

You need to register a callback that performs the certificate lookup/validation. I'm afraid I only have a C# example but something like:

Code:

---

                // Register a callback function to validate the server's X509
                // certificate for SSL
                System.Net.ServicePointManager.ServerCertificateValidationCallback =
              new RemoteCertificateValidationCallback(ValidateServerCertificate);

---

where the callback function is:-

Code:

---

        /// <summary>
        /// Validates a servers X509 certificate
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="certificate"></param>
        /// <param name="chain"></param>
        /// <param name="sslPolicyErrors"></param>
        /// <returns></returns>
        public static bool ValidateServerCertificate(object sender,
                X509Certificate certificate,
                X509Chain chain,
                SslPolicyErrors sslPolicyErrors)
        {
            if (sslPolicyErrors ==
              SslPolicyErrors.RemoteCertificateChainErrors)
            {

                return false;
            }
            else if (sslPolicyErrors ==
              SslPolicyErrors.RemoteCertificateNameMismatch)
            {


                System.Security.Policy.Zone z =
                  System.Security.Policy.Zone.CreateFromUrl
                  (((WebRequest)sender).RequestUri.ToString());
                if (z.SecurityZone ==
                  System.Security.SecurityZone.Intranet ||
                  z.SecurityZone ==
                  System.Security.SecurityZone.MyComputer)
                {

                    return true;
                }

                return false;
            }
            return true;
        }

---