FTP客户端收到网络错误javax.net.ssl.SSLHandshakeExc0019：远程主机在握手过程中关闭连接

Question

我正在尝试连接到需要“通过TLS显式FTP”的FTP并上载文件。

我正在尝试从我的本地机器上实现它，它使用Java版本8和commons net FTP版本3.6

下面是我使用的代码

          try {

              FTPSClient ftpClient = new FTPSClient();


              ftpClient.setDataTimeout(300); 
              ftpClient.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
              ftpClient.setAuthValue("TLS");
              ftpClient.connect(server, port);
              int reply = ftpClient.getReplyCode();


              if (FTPReply.isPositiveCompletion(reply)) {
                  ftpClient.execAUTH("TLS"); //SSL


                // Login
                if (ftpClient.login(user, pass)) {

                  // Set protection buffer size
                  ftpClient.execPBSZ(0);
                  // Set data channel protection to private
                  ftpClient.execPROT("P");
                  // Enter local passive mode
                  ftpClient.enterLocalPassiveMode();
                  ftpClient.changeWorkingDirectory("/");
                  ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
              File firstLocalFile = new File(outputFileNameCSV);
                              String firstRemoteFile = csvFileNameOut;
                  InputStream inputStream = new FileInputStream(firstLocalFile);

                  // Store file on host
                  boolean done = ftpClient.storeFile(firstRemoteFile, inputStream);
              inputStream.close();
              if (done) 
              {
                System.out.println("The file is uploaded successfully.");
              }

              // Logout
              ftpClient.logout();

                } else {
                  System.out.println("FTP login failed");
                }

                // Disconnect
                ftpClient.disconnect();

              } else {
                System.out.println("FTP connect to host failed");
              }
            } catch (IOException ioe) {
              System.out.println("FTP client received network error "+ioe);
            }

下面是我从Java CommandListener获得的日志

220-FileZilla Server 0.9.60 beta
220-written by Tim Kosse ([e-mail])
220 Please visit https://filezilla-project.org/
AUTH TLS
234 Using authentication type TLS
AUTH TLS
534 Authentication type already set to TLS
FTP login screen
USER test
331 Password required for test
PASS pass
230 Logged on
PBSZ 0
200 PBSZ=0
PROT P
200 Protection level set to P
CWD /
250 CWD successful. "/" is current directory.
TYPE I
200 Type set to I
PASV
227 Entering Passive Mode ()
STOR file.csv
150 Opening data channel for file upload to server of "/file.csv"
FTP client received network error javax.net.ssl.SSLHandshakeException: Remote host closed connection during handshake

下面是我尝试使用FileZilla连接时的日志。连接很好，我可以传送文件。

但是，当我尝试使用Java时，它不会传输数据

Response:   220-FileZilla Server 0.9.60 beta
Response:   220-written by Tim Kosse ([e-mail])
Response:   220 Please visit https://filezilla-project.org/
Command:    AUTH TLS
Response:   234 Using authentication type TLS
Status: Initializing TLS...
Status: Verifying certificate...
Command:    USER test
Status: TLS/SSL connection established.
Response:   331 Password required for test
Command:    PASS pass
Response:   230 Logged on
Command:    PBSZ 0
Response:   200 PBSZ=0
Command:    PROT P
Response:   200 Protection level set to P
Status: Connected
Status: Starting upload of file.csv
Command:    CWD /
Response:   250 CWD successful. "/" is current directory.
Command:    TYPE I
Response:   200 Type set to I
Command:    PASV
Response:   227 Entering Passive Mode ()
Command:    STOR file.csv
Response:   150 Opening data channel for file upload to server of "/file.csv"
Response:   226 Successfully transferred "/file.csv"
Status: File transfer successful, transferred 12,252 bytes in 1 second

请大家帮忙好吗？

亲切的问候乔恩

Answer 1

现代FTP服务器期望通过使用TLS会话恢复来打开数据通道。Java能够做到这一点，但只能用于连接到相同的IP和端口。由于FTP会话的数据通道使用不同的端口，因此该机制会失败，因此您需要强制JVM这样做，并包括使用反射对java类的实习生进行大量的修改。

您使用的是ApacheFTPSClient，因此您可能会检查它的最新版本是否已经为您提供了该功能，但如果仍然没有提供，您可以按照Wealthfront博客文章中的描述自行完成。

黑客（我仍然无法用不同的方式称呼它）在客户端工作得很好，但是如果您想在服务器端执行此操作（即，如果您想实现自己的FTP服务器），则还有一些重要的额外工作要做。你的问题看起来不像，所以我在这个答案中省略了这一部分。