FTP File Transfer

[rjjhome]

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?

[jmcilhinney]

Can you show us the code you're using?

[rjjhome]

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

[Merrion]

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

                // 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:-

        /// <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;
        }