嘗試列出ftps服務器上的文件時，FluentFTP拋出“System.IO.IOException：Authentication failed”

Question

說明使用FluentFTP連接到FileZilla FTPS服務器時，我們收到System.IO.IOException: Authentication failed because the remote party has closed the transport stream. 在嘗試列出文件時。

我們可以建立初始連接，我們可以登錄，但是當FluentFTP嘗試通過EPSV建立數據連接時，它會因該異常而出錯。

到目前為止，我們的研究似乎指向TLS恢復失敗。 FTPS服務器堅持數據連接從控制連接恢復TLS會話，這似乎是失敗的。 奇怪的是，這只發生在Linux或WSL上的dotnetcore上。 在Windows上的dotnetcore上一切正常。

版本 ：DotNetCore 2.1.5 FluentFTP 19.2.2

OS Ubuntu 18.04 / Windows 10 WSL Ubuntu 18.04

演示代碼

public async Task We_should_be_able_to_connect_and_list_files()
{
    var client = new FtpClient("myhost", "user", "pass");
    client.EncryptionMode = FtpEncryptionMode.Explicit;
    client.SslProtocols = SslProtocols.Tls;
    client.ValidateCertificate += (c, e) => { e.Accept = true; };

    await client.ConnectAsync();
    var items = await client.GetListingAsync("/");

    Assert.NotEmpty(items);
}

例外

System.IO.IOException : Authentication failed because the remote party has closed the transport stream.
   at System.Net.Security.SslState.StartReadFrame(Byte[] buffer, Int32 readBytes, AsyncProtocolRequest asyncRequest)
   at System.Net.Security.SslState.PartialFrameCallback(AsyncProtocolRequest asyncRequest)
--- End of stack trace from previous location where exception was thrown ---
   at System.Net.Security.SslState.ThrowIfExceptional()
   at System.Net.Security.SslState.InternalEndProcessAuthentication(LazyAsyncResult lazyResult)
   at System.Net.Security.SslState.EndProcessAuthentication(IAsyncResult result)
   at System.Net.Security.SslStream.EndAuthenticateAsClient(IAsyncResult asyncResult)
   at System.Net.Security.SslStream.<>c.<AuthenticateAsClientAsync>b__46_2(IAsyncResult iar)
   at System.Threading.Tasks.TaskFactory`1.FromAsyncCoreLogic(IAsyncResult iar, Func`2 endFunction, Action`1 endAction, Task`1 promise, Boolean requiresSynchronization)
--- End of stack trace from previous location where exception was thrown ---
   at FluentFTP.FtpSocketStream.ActivateEncryptionAsync(String targethost, X509CertificateCollection clientCerts, SslProtocols sslProtocols)
   at FluentFTP.FtpClient.OpenPassiveDataStreamAsync(FtpDataConnectionType type, String command, Int64 restart)
   at FluentFTP.FtpClient.OpenDataStreamAsync(String command, Int64 restart)
   at FluentFTP.FtpClient.GetListingAsync(String path, FtpListOption options)

FluentFTP日志

...

# GetListingAsync("/", Auto)
Command:  TYPE I
Response: 200 Type set to I

# OpenPassiveDataStreamAsync(AutoPassive, "MLSD /", 0)
Command:  EPSV
Response: 229 Entering Extended Passive Mode (|||50992|)
Status:   Connecting to ***:50992
Command:  MLSD /
Response: 150 Opening data channel for directory listing of "/"
Status:   Disposing FtpSocketStream...

我們做錯了什么？