“Authentication failed because the remote party has closed the transport stream” when transferring to/from FTP server over TLS/SSL using FluentFTP

问题

I have used FluentFTP lib im my project to work with FTP via TLS, but some trouble here.

This code working fine:

using (var conn = new FtpClient("adress", "user", "password"))
{
    conn.EncryptionMode = FtpEncryptionMode.Explicit;
    conn.ValidateAnyCertificate = true;
    conn.Connect();

    conn.CreateDirectory("/test/path/that/should/be/created", true);
}

And directory were created. But in other examples it not working good.

First exmple (logfile - https://pastebin.com/jNyZ3fmD):

public static void DownloadFile()
{
    using (var conn = new FtpClient("adress", "user", "password"))
    {
        conn.EncryptionMode = FtpEncryptionMode.Explicit;
        conn.ValidateAnyCertificate = true;
            conn.Connect();

        conn.DownloadFile("localPath", "ftpPath", FtpLocalExists.Overwrite, FtpVerify.Retry);

    }
}

I have error:

"Error while uploading the file to the server. See InnerException for more info." IOException: Authentication failed because the remote party has closed the transport stream

Trying to get file/dir-list from FTP using code below return nothing in console (logfile - https://pastebin.com/V8AiLs8k):

using (var conn = new FtpClient("adress", "user", "password"))
{
    //conn.Connect();
    conn.EncryptionMode = FtpEncryptionMode.Explicit;
    conn.ValidateCertificate += new FtpSslValidation(OnValidateCertificate);
    conn.Connect();

    // get a recursive listing of the files & folders in a specific folder
    foreach (var item in conn.GetListing())
    {
        switch (item.Type)
        {

            case FtpFileSystemObjectType.Directory:

                Console.WriteLine("Directory!  " + item.FullName);
                Console.WriteLine("Modified date:  " + conn.GetModifiedTime(item.FullName));

                break;

            case FtpFileSystemObjectType.File:

                Console.WriteLine("File!  " + item.FullName);
                Console.WriteLine("File size:  " + conn.GetFileSize(item.FullName));
                Console.WriteLine("Modified date:  " + conn.GetModifiedTime(item.FullName));
                Console.WriteLine("Chmod:  " + conn.GetChmod(item.FullName));

                break;

            case FtpFileSystemObjectType.Link:
                break;
        }
        Console.WriteLine(item);
    }

}

The user has the privilege to download, create and delete files. But I can only make a dir on server.

回答1:

It seems to be due to a lack of TLS session resumption support in FluenFTP:
https://github.com/robinrodricks/FluentFTP/issues/347

If you confirm that with the server owner, you will have to switch to another FTP library. For a similar question (for an implicit TLS, while you are using an explicit TLS) see:
Upload file to implicit FTPS server in C# with TLS session reuse

Or ask the owner to turn off session resumption requirement (though that's bad from a security point of view).

来源：https://stackoverflow.com/questions/61068219/authentication-failed-because-the-remote-party-has-closed-the-transport-stream

标签

.net

ssl

ftp

fluentftp