使用C＃.Net通过FTPS（SSL/TLS）传输文件

Question

我正在编写一个通过FTP站点同步文件的应用程序。目前它通过普通FTP进行连接，但现在我们的IT人员希望通过安全的FTPS连接进行设置。

他们向我提供了* .cr_证书文件。如果我在记事本中打开文件，我会看到类似的东西（但显然，真正的键不是foobar）。

-----BEGIN RSA PRIVATE 
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR 
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
-----END RSA PRIVATE KEY----- 
-----BEGIN CERTIFICATE----- 
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
FOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBARFOOBAR  
-----END CERTIFICATE----- 

如何使用此证书文件连接到FTPS服务器上传和下载文件？请原谅我，但我很新的，涉及在网络上传输的文件，安全的连接，证书，公钥，私钥等...等什么...

我想我会想使用的FtpWebRequest对象并将EnableSsl属性设置为true。但我不确定这个证书文件在哪里发挥作用。

Answer 1

This article解释了如何使用源代码。

这篇文章的目的是在安全模式下创建一个C＃的FTP客户端，所以如果你没有FTPS的很多知识，我建议你看看这个：FTPS。

在.NET Framework中，要以FTPS模式上传文件，我们通常使用FtpWebRequest类，但不能使用引号参数发送命令，即使您在网上搜索，也不会找到具体的一个安全的C＃FTP客户端的例子。

这是由于这些原因，我决定创建这篇文章。

Answer 2

如果您使用FtpWebRequest Class，则只需在请求的设置中添加一些内容即可。一定要包括using System.Security.Cryptography.X509Certificates;声明。

FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpUrl); 
    request.Credentials = new NetworkCredential(userName, password); 

    request.EnableSsl = true; 
    //ServicePointManager.ServerCertificateValidationCallback = ServicePointManager_ServerCertificateValidationCallback; 

    X509Certificate cert = X509Certificate.CreateFromCertFile(@"C:\MyCertDir\MyCertFile.cer"); 
    X509CertificateCollection certCollection = new X509CertificateCollection(); 
    certCollection.Add(cert); 

    request.ClientCertificates = certCollection; 

此外，如果你有，你可能需要实现与ServicePointManager.ServerCertificateValidationCallback Property使用自己的证书验证回调方法的证书生成异常问题。这可以简单一如既往返回true或更复杂的像我用于调试：

public static bool ServicePointManager_ServerCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) 
    { 
     bool allowCertificate = true; 

     if (sslPolicyErrors != SslPolicyErrors.None) 
     { 
      Console.WriteLine("Accepting the certificate with errors:"); 
      if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNameMismatch) == SslPolicyErrors.RemoteCertificateNameMismatch) 
      { 
       Console.WriteLine("\tThe certificate subject {0} does not match.", certificate.Subject); 
      } 

      if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateChainErrors) == SslPolicyErrors.RemoteCertificateChainErrors) 
      { 
       Console.WriteLine("\tThe certificate chain has the following errors:"); 
       foreach (X509ChainStatus chainStatus in chain.ChainStatus) 
       { 
        Console.WriteLine("\t\t{0}", chainStatus.StatusInformation); 

        if (chainStatus.Status == X509ChainStatusFlags.Revoked) 
        { 
         allowCertificate = false; 
        } 
       } 
      } 

      if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNotAvailable) == SslPolicyErrors.RemoteCertificateNotAvailable) 
      { 
       Console.WriteLine("No certificate available."); 
       allowCertificate = false; 
      } 

      Console.WriteLine(); 
     } 

     return allowCertificate; 
    }