C# FTPS FtpWebRequest 设置被动模式使用端口范围

Question

我无法使用 C# FtpWebRequest.

连接到特定 FTP

使用 TotalCommander 或 FileZilla 我可以连接。

关于FTP的信息说：

FTPS – 隐式 SSL/TLS
端口 990
被动端口范围：60000–60100

另一个 FTP 效果很好。

var remoteFile = "ftp://ADDRESS:990/FILE.csv";
var localFile = Server.MapPath("~/tmp/file.csv");

int bufferSize = 2048;

if (!Directory.Exists(Path.GetDirectoryName(localFile)))
    Directory.CreateDirectory(Path.GetDirectoryName(localFile));
/* Create an FTP Request */
FtpWebRequest ftpRequest = (FtpWebRequest)FtpWebRequest.Create(remoteFile);
/* Log in to the FTP Server with the User Name and Password Provided */
ftpRequest.Credentials = new NetworkCredential("USER", "PWD");
/* When in doubt, use these options */
ftpRequest.UseBinary = true;
ftpRequest.UsePassive = true;
ftpRequest.KeepAlive = true;

ftpRequest.EnableSsl = true;
// Always returns true
ServicePointManager.ServerCertificateValidationCallback = OnValidateCertificate; 

/* Specify the Type of FTP Request */
ftpRequest.Method = WebRequestMethods.Ftp.DownloadFile;
/* Establish Return Communication with the FTP Server */
FtpWebResponse ftpResponse = (FtpWebResponse)ftpRequest.GetResponse();
/* Get the FTP Server's Response Stream */
Stream ftpStream = ftpResponse.GetResponseStream();
/* Open a File Stream to Write the Downloaded File */
FileStream localFileStream = new FileStream(localFile, FileMode.Create);
/* Buffer for the Downloaded Data */
byte[] byteBuffer = new byte[bufferSize];
int bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
/* Download the File by Writing the Buffered Data Until the Transfer is Complete */
try
{
    while (bytesRead > 0)
    {
        localFileStream.Write(byteBuffer, 0, bytesRead);
        bytesRead = ftpStream.Read(byteBuffer, 0, bufferSize);
    }
}
catch (Exception ex)
{
    Console.WriteLine(ex.ToString());
}
/* Resource Cleanup */
localFileStream.Close();
ftpStream.Close();
ftpResponse.Close();
ftpRequest = null;

我认为错误是由被动端口范围 60000–60100 引起的。但是不知道怎么设置。

Answer 1

FTP 被动端口范围是 server-side 配置。

您没有在客户端端设置被动端口范围——FileZilla和Total Commander也没有这样的配置选项。 FTP 客户端使用服务器 选择的端口 。

您的实际问题是 .NET/FtpWebRequest 不支持 implicit TLS/SSL:
Does .NET FtpWebRequest Support both Implicit (FTPS) and explicit (FTPES)?

Answer 2

您将永远无法从 Microsoft 框架连接到隐式 FTPS。它是一个不安全的旧第三方框架。将客户端更改为显式 FTPS。

C# FTPS FtpWebRequest 设置被动模式使用端口范围

C# FTPS FtpWebRequest set passive mode to use port range

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