具有WebClient错误的C＃FTP：远程服务器返回错误：（534）534策略需要SSL

Question

The purpose of my code is to upload some data to a FTP location.

With my code I keep getting an error stating that the remote server requires SSL. I am using a .NET version greater then 4. All the other posts suggest I add the ServicePointManager code that I have below.

The exception occurs on client.UploadData .

Still no dice. Any help would be very much appreciated.

ServicePointManager.ServerCertificateValidationCallback +=
    (sender,certificate, chain, sslPolicyErrors) => true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
byte[] data = stream.ToArray(); //Data I want to upload to FTP location

using (WebClient client = new WebClient())
{
    client.Credentials = new NetworkCredential("*Username*", "*Password*");
    client.UploadData("ftp://file.example.com/Content/file", "STOR", data);
}

Answer 1

Afaik, WebClient does not support FTP over TLS (FTPS) natively (it actually does support it internally , but has no API to enable its use).

Setting ServicePointManager.SecurityProtocol cannot help. And definitely do not set it to SecurityProtocolType.Ssl3 !

---

• either register ftps:// prefix as shown for example here: Force WebClient to use SSL .

• or instead of WebClient , use FtpWebRequest , which supports FTP over TLS natively.

  Use a code like this:
  Upload and download a binary file to/from FTP server in C#/.NET

  And just add

   request.EnableSsl = true;