我正在使用带有Java 8的Apache Commons Net(v3.5)来连接到远程FTPS站点(即在Internet上)。我能够轻松地与Windows 10计算机上的FileZilla客户端连接,但是我的Java程序无法完成相同的步骤。我已经在谷歌上搜索了,但找不到根本原因。这是我已经确认的事情:
我确保Java FTP命令的顺序与FileZilla客户端的顺序完全相同。
我在PC上禁用了Windows防火墙和防病毒
我重新启用了Windows防火墙并启用了日志记录。使用FileZilla时,在建立被动模式连接时,Windows防火墙日志会列出TCP连接。我在Java程序中看不到这样的条目。
我在PC上安装了FileZilla服务器。我取消选中“使用PROT P时要求在数据连接上恢复TLS会话”后,该Java程序正常工作。 Java异常是不同的,因此我不认为这是一支抽烟的枪。
我在test.rebex.com服务器上成功运行了相同的代码。
以下是代码,任何想法都将不胜感激:
import java.io.IOException;
import java.io.PrintWriter;
import org.apache.commons.net.PrintCommandListener;
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;
import org.apache.commons.net.ftp.FTPSClient;
public class testProgram {
public static void main(String[] args) {
String ftpServer = "ftp.domain.com";
String ftpUsername = "user@domain.com";
String ftpPassword = "********";
FTPSClient ftp = null;
// CONNECT TO THE SERVER
try {
// I have tried "SSL" as the argument, but same result
ftp = new FTPSClient();
ftp.addProtocolCommandListener(new PrintCommandListener(new PrintWriter(System.out)));
ftp.connect(ftpServer,21);
int reply = ftp.getReplyCode();
if (!FTPReply.isPositiveCompletion(reply)) {
ftp.disconnect();
System.err.println("---------->FTP server refused connection.\n");
}
} catch (Exception e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
// LOGIN INTO SERVER
try {
if (!ftp.login(ftpUsername, ftpPassword)) {
ftp.logout();
} else {
ftp.sendCommand("OPTS UTF8 ON");
ftp.execPBSZ(0);
ftp.execPROT("P");
ftp.pwd();
ftp.setFileType(FTP.BINARY_FILE_TYPE);
ftp.enterLocalPassiveMode();
/* The next command always fails.
The FTP Server responds with "150 Accepted data connection" then:
org.apache.commons.net.ftp.FTPConnectionClosedException: Connection closed without indication.
at org.apache.commons.net.ftp.FTP.__getReply(FTP.java:316)
at org.apache.commons.net.ftp.FTP.__getReply(FTP.java:292)
at org.apache.commons.net.ftp.FTP.getReply(FTP.java:712)
at org.apache.commons.net.ftp.FTPClient.completePendingCommand(FTPClient.java:1857)
at org.apache.commons.net.ftp.FTPClient.listNames(FTPClient.java:2919)
at org.apache.commons.net.ftp.FTPClient.listNames(FTPClient.java:2952)
at myPackage.testProgram.main(testProgram.java:78)
I have tried other commands, but it disconnects here...
*/
FTPFile[] ftpFiles = ftp.listFiles();
System.out.println("---------->Number of Files = " + ftpFiles.length);
ftp.logout();
}
} catch (Exception e) {
e.printStackTrace();
}
//Ensure Disconnected at the end.
if (ftp.isConnected()) {
try {
ftp.disconnect();
} catch (IOException f) {
// do nothing
}
}
}
}
这是我PC上的FileZilla Client日志:
2016-09-06 09:09:50 4756 1 Status: Resolving address of ftp.domain.com
2016-09-06 09:09:51 4756 1 Status: Connecting to h1.h2.h3.h4:21...
2016-09-06 09:09:51 4756 1 Status: Connection established, waiting for welcome message...
2016-09-06 09:09:51 4756 1 Response: 220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
2016-09-06 09:09:51 4756 1 Response: 220-You are user number 2 of 50 allowed.
2016-09-06 09:09:51 4756 1 Response: 220-Local time is now 13:09. Server port: 21.
2016-09-06 09:09:51 4756 1 Response: 220-This is a private system - No anonymous login
2016-09-06 09:09:51 4756 1 Response: 220-IPv6 connections are also welcome on this server.
2016-09-06 09:09:51 4756 1 Response: 220 You will be disconnected after 15 minutes of inactivity.
2016-09-06 09:09:51 4756 1 Command: AUTH TLS
2016-09-06 09:09:51 4756 1 Response: 234 AUTH TLS OK.
2016-09-06 09:09:51 4756 1 Status: Initializing TLS...
2016-09-06 09:09:51 4756 1 Status: Verifying certificate...
2016-09-06 09:09:51 4756 1 Status: TLS connection established.
2016-09-06 09:09:51 4756 1 Command: USER user@domain.com
2016-09-06 09:09:51 4756 1 Response: 331 User user@domain.com OK. Password required
2016-09-06 09:09:51 4756 1 Command: PASS *************
2016-09-06 09:09:51 4756 1 Response: 230 OK. Current restricted directory is /
2016-09-06 09:09:51 4756 1 Command: SYST
2016-09-06 09:09:51 4756 1 Response: 215 UNIX Type: L8
2016-09-06 09:09:51 4756 1 Command: FEAT
2016-09-06 09:09:51 4756 1 Response: 211-Extensions supported:
2016-09-06 09:09:51 4756 1 Response: EPRT
2016-09-06 09:09:51 4756 1 Response: IDLE
2016-09-06 09:09:51 4756 1 Response: MDTM
2016-09-06 09:09:51 4756 1 Response: SIZE
2016-09-06 09:09:51 4756 1 Response: MFMT
2016-09-06 09:09:51 4756 1 Response: REST STREAM
2016-09-06 09:09:51 4756 1 Response: MLST type*;size*;sizd*;modify*;UNIX.mode*;UNIX.uid*;UNIX.gid*;unique*;
2016-09-06 09:09:51 4756 1 Response: MLSD
2016-09-06 09:09:51 4756 1 Response: AUTH TLS
2016-09-06 09:09:51 4756 1 Response: PBSZ
2016-09-06 09:09:51 4756 1 Response: PROT
2016-09-06 09:09:51 4756 1 Response: UTF8
2016-09-06 09:09:51 4756 1 Response: TVFS
2016-09-06 09:09:51 4756 1 Response: ESTA
2016-09-06 09:09:51 4756 1 Response: PASV
2016-09-06 09:09:51 4756 1 Response: EPSV
2016-09-06 09:09:51 4756 1 Response: SPSV
2016-09-06 09:09:51 4756 1 Response: ESTP
2016-09-06 09:09:51 4756 1 Response: 211 End.
2016-09-06 09:09:51 4756 1 Command: OPTS UTF8 ON
2016-09-06 09:09:51 4756 1 Response: 200 OK, UTF-8 enabled
2016-09-06 09:09:51 4756 1 Command: PBSZ 0
2016-09-06 09:09:51 4756 1 Response: 200 PBSZ=0
2016-09-06 09:09:51 4756 1 Command: PROT P
2016-09-06 09:09:52 4756 1 Response: 200 Data protection level set to "private"
2016-09-06 09:09:52 4756 1 Status: Logged in
2016-09-06 09:09:52 4756 1 Status: Retrieving directory listing...
2016-09-06 09:09:52 4756 1 Command: PWD
2016-09-06 09:09:52 4756 1 Response: 257 "/" is your current location
2016-09-06 09:09:52 4756 1 Command: TYPE I
2016-09-06 09:09:52 4756 1 Response: 200 TYPE is now 8-bit binary
2016-09-06 09:09:52 4756 1 Command: PASV
2016-09-06 09:09:52 4756 1 Response: 227 Entering Passive Mode (h1,h2,h3,h4,133,150)
2016-09-06 09:09:52 4756 1 Command: MLSD
2016-09-06 09:09:52 4756 1 Response: 150 Accepted data connection
2016-09-06 09:09:52 4756 1 Response: 226-Options: -a -l
2016-09-06 09:09:52 4756 1 Response: 226 6 matches total
根据Mike的建议,我打开了TLS调试功能。看来程序再次通过TLS握手。输出非常长,但是发出list命令后,我看到“ *** ClientHello,TLSv1.2”,看起来像与启动FTP连接相同的命令。
差异似乎出现在最后:
%% Cached client session: [Session-2, TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256]
main, received EOFException: ignored
main, called closeInternal(false)
main, SEND TLSv1.2 ALERT: warning, description = close_notify
main, WRITE: TLSv1.2 Alert, length = 26
main, called closeSocket(false)
main, called close()
main, called closeInternal(true)
main, called close()
main, called closeInternal(true)
main, received EOFException: ignored
main, called closeInternal(false)
main, SEND TLSv1.2 ALERT: warning, description = close_notify
main, WRITE: TLSv1.2 Alert, length = 26
main, called closeSocket(false)
org.apache.commons.net.ftp.FTPConnectionClosedException: Connection closed without indication.
最佳答案
尽管这看起来像是一篇老文章,但今天我遇到了类似的问题,无法(最初)找到解决方案。我可以通过FileZilla进行连接,但不能与FTPSClient连接,并且在运行ftpClient.enterLocalPassiveMode()
之后,我通常会获得425 cannot open data connection
我的解决方案是在登录之前但在连接到FTPServer之后更改ftpClient.enterLocalPassiveMode()
并起作用。通常,我看到的所有代码示例在发送/接收数据之前但登录后都使用enterlocalpassivemode
。请参阅以下代码,该示例对我有用。
FTPSClient ftpClient = new FTPSClient(false);
ftpClient.connect("remote.ftp.server", port);
ftpClient.enterLocalPassiveMode();// Run the passive mode command now instead of after loggin in.
ftpClient.login("username", "password");
ftpClient.execPBSZ(0);
ftpClient.execPROT("P");
ftpClient.type(FTP.BINARY_FILE_TYPE);
//ftpClient.enterLocalPassiveMode(); Previously it was here.
FTPFile[] files = ftpClient.listDirectories("/");
希望这可以帮助。还请注意,省略了所有其他代码和良好做法,以使答案简短。