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java: getting Connection refused when trying to upload file to FTP

When trying to upload file to FTP with java program:
public void upload(String localFile,String remoteFile) throws Exception{
ftp = new FTPClient();
ftp.setControlKeepAliveTimeout(300);
ftp.connect(host,21);
ftp.enterLocalPassiveMode();
ftp.setUseEPSVwithIPv4(false);
ftp.login(user,password);
ftp.setFileType(FTPClient.BINARY_FILE_TYPE);
FileInputStream in = null;
in = new FileInputStream(localFile);
ftp.storeFile(remoteFile,in);
in.close();
ftp.disconnect();
}
I'm getting:
java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:381)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:243)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:230)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:377)
at java.net.Socket.connect(Socket.java:539)
at org.apache.commons.net.SocketClient._connect(SocketClient.java:243)
at org.apache.commons.net.SocketClient.connect(SocketClient.java:202)
When I try to upload the same file with command line (from linux), I'm able to do it only when using EPSV:
llnx:~ ftp anonymous#9.20.1.116
Connected to 9.20.1.116.
220 Microsoft FTP Service
331 Anonymous access allowed, send identity (e-mail name) as password.
Password:
230 User logged in.
Remote system type is Windows_NT.
ftp> epsv
EPSV/EPRT on IPv4 off.
ftp> put /tmp/file1.xml /dir_1/file1.xml
local: /tmp/file1.xml remote: /dir_1/file1.xml
227 Entering Passive Mode (10,40,1,149,233,168).
125 Data connection already open; Transfer starting.
100% |*************************************| 117 KB 28.66 MB/s --:-- ETA
226 Transfer complete.
120032 bytes sent in 00:00 (7.96 MB/s)
So, Why does my java code getting Connection refused?
Maybe I'm not using the enterLocalPassiveMode() or setUseEPSVwithIPv4() method the right way?
*** I think the answer is how to run the EPSV command from Java program.
Thank you all.
Eithan.

This is purely a guess but java.net.ConnectException: Connection refused normally happens when there is nothing listening on the target host/port. You don't specify a port in the CLI example so maybe that is the problem. Try changing ftp.connect(host,21); to ftp.connect(host); to use the default. Also confirm the the hostnames are exactly the same.
This assumes that the error is on the call to connect(). You haven't provided a big enough stack trace to indicate either way.

Connection refused means that your TCP connection request has reached the remote server (or more correctly >>a<< remote server) but the server is not expecting / listening for an incoming connection. So it "refuses" it.
Here are the things to check:
Check that you have the correct remote hostname or IP address for the FTP server.
Check that you are using the correct port for the FTP server. Port 21 is the default, but it is possible that the server is on a non-standard port.
Check that the FTP server is actually running.
It is also possible that the problem is due to a firewall doing something deliberately confusing. But that is unlikely for a publicly routable FTP server.
Maybe I'm not using the enterLocalPassiveMode() or setUseEPSVwithIPv4() method the right way?
That can't be the problem. The stacktrace shows that your application failed while trying to establish the initial connection to the server. You haven't gotten to the point where the you can make those calls.

Java ftp4j - List files in FTP server when connecting in amn active mode

I am using ftp4j library to implement my FTP clients however a server that I am trying to connect accept connections only in active mode.
So when I am trying to list remote files i am getting:
ERROR : Error in Connecting to Remote Machine... Hence exitting...
it.sauronsoftware.ftp4j.FTPException [code=501, message= Server cannot accept argument.]
at it.sauronsoftware.ftp4j.FTPClient.openActiveDataTransferChannel(FTPClient.java:3600)
at it.sauronsoftware.ftp4j.FTPClient.openDataTransferChannel(FTPClient.java:3551)
at it.sauronsoftware.ftp4j.FTPClient.listNames(FTPClient.java:2335)
at com.npap.network.TranferFileFtp4j.listRemoteFilesFtp1(TranferFileFtp4j.java:999)
Here is the code:
...
//connect to server method - in active mode!
ftpClient = Ftp4jUtility.connect1(SERVER_MACHINE, PORT, SERVER_USERNAME, SERVER_PASSWORD);
try {
ftpClient.changeDirectory(config.getFtpRemoteFolderReports());
log.info("Changed directory to: " + config.getFtpRemoteFolderReports());
} catch (FTPException | FTPIllegalReplyException | IOException | IllegalStateException e) {
e.printStackTrace();
}
String[] filesList = ftpClient.listNames();
for(String f: filesList) {
log.info("fetched file: " + f);
tmpAllRemoteFiles.add(f);
}
Any way to list remote files when connecting in active mode?

Yes, you can use the .listNames() in the active mode.
The problem is likely that the server cannot connect back to your client to open the data connection. You have to open the ports from FTP data connection range on your local firewall (if any), as well as route the incoming connections on your NAT (if any).
Configuring the active mode FTP is cumbersome and is rarely used.
Learn (my) article about required network configuration in respect to FTP active mode.
The 501 error code comes from the FTP server (IIS likely). You will find lots of similar problems, if you google for "501 Server cannot accept argument".
There's nothing wrong with your code. It's either the network configuration or server-side problem.

ftp4j java ftpClient manage connection failures during file upload

I am trying to implement an ftpClient interface which would be able to manage network connection issues. I am using the ftp4j library for this purpose.
I can succesfully upload files BUT i have some issues when a connection failure appears during a file upload process. I would like to be able to re-upload (not append, just start again) the file just after a connection issue terminate my previous upload attempt.
The case is that if i try to re-try uploading the file some seconds or even minutes after the previous unsuccesful attemp i am getting:
it.sauronsoftware.ftp4j.FTPException [code=550, message= Access is denied. ]
at it.sauronsoftware.ftp4j.FTPClient.upload(FTPClient.java:2794)
at it.sauronsoftware.ftp4j.FTPClient.upload(FTPClient.java:2586)
If i wait some time and then re-try, i will be able to upload the file to the FTP server.
Is it some parameter that i could set to my ftpClient:
...
FTPClient client = new FTPClient();
try {
client.setType(FTPClient.TYPE_BINARY);
client.connect(ipAddress, port);
client.login(userName, password);
System.out.println("Connected to FTP Server!");
...
}
...
if(ftpClient.isResumeSupported()) {
System.err.println("FTP Server supports resume. Trying to upload file");
ftpClient.upload(localFile, writtenBytes, new Ftp4jListener());
} else {
System.err.println("FTP Server does NOT supports resume. Trying to upload file");
ftpClient.upload(localFile, new Ftp4jListener());
}
...
for being able to overcome this "Access is denied" problem?
Any ideas what is it causing such an exception? Maybee a server parameter?

JSch causes packet size exceeds maximum allowed error

I am attempting to use the JSch class (Java Secure Channel; jsch-0.1.50.jar) to connect to an SFTP server and send a file from within a ColdFusion (9.0.2) application (which runs atop Java 1.7.0_15). The basic code in question is:
jsch = classLoader.create("com.jcraft.jsch.JSch").init(); // ColdFusion-specific to load the jar
jschSession = jsch.getSession("myusername", "ftp.example.com", 22);
jschSession.setConfig("StrictHostKeyChecking", "no");
jschSession.setTimeout(60000);
jschSession.setPassword("mypassword");
jschSession.connect();
Upon connection to a Serv-U SFTP server it is giving me the following error on the Serv-U side immediately after the connection opens:
SSH Protocol Error: packet size exceeds maximum allowed.
Serv-U then closes the session, at which point JSch throws the exception:
Session.connect: java.io.IOException: End of IO Stream Read
I am new to the JSch class, and it's possible I'm missing something obvious, but I am at a loss as to where the error may lie. Connecting to the same SFTP server from the same origin with WinSCP gives no errors. Any tips on what the code is doing wrong or where to turn next for troubleshooting?

SSH Protocol Error: packet size exceeds maximum allowed
This means that the local client received some data from the remote server which wasn't properly formatted as an SFTP protocol message. The usual reason is that the server sent some kind of plain text message through the SSH connection. There are few things that might be going on:
Your .bashrc, .bash_profile, or similar shell configuration file on the server is set to print some message.
The server is poorly configured, and it's sending some kind of greeting.
The server is sending some kind of error message.
If you have access to the ssh command-line utility, you can use that to see what the server is sending. Run something like this:
$ ssh myusername#ftp.example.com -s sftp
This will open a plain SSH session to the remote server and request the SFTP subsystem, which is the same thing an SFTP client would do. If the server starts SFTP properly, you won't see any output from this command--it'll just wait until you kill it. If you see any text from the remote server, that is the problem. You'll need to figure out why the server is sending that text and prevent it.

Manual FTP with commons.net.ftp

I am trying to use apache commons to send manual FTP commands as I have to send non-standard FTP commands to a specific server (that accepts them)
Before I try to send these non-standard commands I want to get FTP working manually with commons.net.ftp. Unfortunately I seem to be missing something.
This works fine (i.e. it retrieves the list of files)
FTPClient ftp = new FTPClient();
FTPClientConfig config = new FTPClientConfig();
ftp.configure(config);
ftp.connect("ftp.mozilla.org");
ftp.login("anonymous", "");
ftp.enterLocalPassiveMode();
FTPFile[] fileList = ftp.listFiles("/");
This doesn't
FTPClient ftp = new FTPClient();
FTPClientConfig config = new FTPClientConfig();
ftp.configure(config);
ftp.connect("ftp.mozilla.org");
ftp.login("anonymous", "");
ftp.sendCommand("PASV");
ftp.sendCommand("NLST");
I get the appropriate response for ftp.sendCommand("PASV"); but it times out on ftp.sendCommand("NLST"); finally giving me
425 Failed to establish connection.
I have tried to research the topic but most advice on this error is for people setting up servers (and it's usually a firewall problem).
Why does it work when net.ftp does it, but not when I send the commands manually?

Sending the PASV command manually is not enough, the client has to open the data connection to the port specified by the server in response to the PASV command. This is performed by calling the enterLocalPassiveMode() method. Since sending PASV manually doesn't initialize the data connection you get an error shortly after.
See http://slacksite.com/other/ftp.html#passive for more details on the FTP protocol.