[JSch-users] Session.connect(): Connection refused

[A Y. <aya...@ya...>]

Hi,

I'm looking for some advice on how I would troubleshoot the following exception: 

The code in question runs properly on an Ubuntu development workstation, and I am able to connect via the sftp cilent on the deployment environment (Red Hat). However, executing the code on Red Hat results in the 'Connection refused' error. I can also telnet to the remote SFTP server on port 22 from the deployment box.

com.jcraft.jsch.JSchException: java.net.ConnectException: Connection refused
	at com.jcraft.jsch.Util.createSocket(Util.java:389)
	at com.jcraft.jsch.Session.connect(Session.java:215)
	at com.jcraft.jsch.Session.connect(Session.java:183)
	at com.xyz.sftp.SFTPService.connect(SFTPService.java:107)
	at com.xyz.sftp.SFTPService.init(SFTPService.java:46)
	at com.xyz.sftp.SFTPUtility.init(SFTPUtility.java:44)
	at com.xyz.sftp.SFTPUtility.run(SFTPUtility.java:50)
	at com.xyz.sftp.SFTPUtility.execute(SFTPUtility.java:67)
	at com.xyz.sftp.SFTPUtility.main(SFTPUtility.java:44)
Exception in thread "main" java.lang.RuntimeException: java.net.ConnectException: Connection refused
	at com.xyz.sftp.SFTPService.init(SFTPService.java:50)
	at com.xyz.sftp.SFTPUtility.init(SFTPUtility.java:44)
	at com.xyz.sftp.SFTPUtility.run(SFTPUtility.java:50)
	at com.xyz.sftp.SFTPUtility.execute(SFTPUtility.java:67)
	at com.xyz.sftp.SFTPUtility.main(SFTPUtility.java:44)
Caused by: com.jcraft.jsch.JSchException: java.net.ConnectException: Connection refused
	at com.jcraft.jsch.Util.createSocket(Util.java:389)
	at com.jcraft.jsch.Session.connect(Session.java:215)
	at com.jcraft.jsch.Session.connect(Session.java:183)
	at com.xyz.sftp.SFTPService.connect(SFTPService.java:107)
	at com.xyz.sftp.SFTPService.init(SFTPService.java:46)
	... 4 more

As part of the init process, I load a known_hosts file and a private key from file:

public void init() {
        try {
            loadKnownHosts();

            byte[] privateKey = readPrivateKeyFromFile(_keyFileName);
            addIdentity(_userId, privateKey, _passPhrase.getBytes());
            connect(_server, _userId);
        }
        catch(Exception e) {
            throw new RuntimeException(e.getMessage(), e);
        }
    }

    protected void connect(String server, String userId) throws JSchException {
        _session = _jsch.getSession(userId, server, 22);
        _session.setDaemonThread(true);
        _session.setServerAliveInterval(5000); // keep alive messages
        _session.connect();  // ***** EXCEPTION OCCURS ON THIS LINE
        Channel channel = _session.openChannel("sftp");
        _sftpChannel = (ChannelSftp) channel;
        _sftpChannel.connect();
    }

I can confirm that the private key is loaded properly, but I can't really tell if my known_hosts file is causing the problem. Could an invalid known_hosts file result in a 'Connection refused' error?

Thanks for your time