java.net.ConnectException: Connection timed out, Post deployment of jsch-0.2.20.jar

[AbhishekSingh9996]

I have been using a generic code to create Connection with different data providers but due to key exchange alogirthms limitations for vendor 1 i had to deploy the jsch-0.2.20 jar within the application. Post deployment the Algorithm Negotation Failed was resolved for that data vendor 1 but one perfectly working connection (data vendor 2) is facing failure now. I was facing Algorithm Negotation Failed for ssh-rsa host key that was resolved appending the same in session.config but now i am facing java.net.ConnectException: Connection timed out.
(Also with backporting to older jsch version the connection starts working fine with data-vendor2 again.)
The code base is as below along with some important info logger statements revealing the issue is occuring just at session.connect().

Code:

public void connect(String hostName, int port, String user, String passWord) throws RBException {
System.out.println("Accessing the connect method");
logger.info("Trying to log in on server " + hostName + " as user " + user);
logger.info("Entered method 1 of connect");

JschSFTP loge = new JschSFTP();
JSch.setLogger(loge);

logger.info("Trying to log in on server " + hostName + " as user " + user);

this.hostName = hostName;
this.user = user;
this.passWord = passWord;
JSch jSch = new JSch();

try {
	session = jSch.getSession(user, hostName, port);
	logger.info("Block 1 user,Hostname and port are : "+user+", "+hostName+", "+port);
	config.put("StrictHostKeyChecking", "no");
	session.setConfig(config);
	session.setTimeout(timeOut * 1000);
	session.setPassword(passWord);

	session.connect();
	
	channel = session.openChannel("sftp");
	sftp = (ChannelSftp) channel;
	sftp.connect();

	loggedIn = true;
	logger.error("User " + user + " successfully logged in on server " + hostName);
	cwd = sftp.pwd();
} catch (JSchException e) {
	try {
		logger.info("Entered catch of method 1");
		logger.info("The error message in catch 1 is : "+e.getMessage());
		if (e.getMessage().contains("java.security.InvalidAlgorithmParameterException")||e.getMessage().contains("Algorithm negotiation fail")) {
			session.disconnect();
			Security.insertProviderAt(new BouncyCastleProvider(), 1);
			if(proxyHost==null || proxyHost.isEmpty()) {
				proxyPort=0;
			}
			session = getSession(jSch, hostName, user, passWord, 22, proxyHost, proxyPort);
			logger.info("Session setup done");
			logger.info("Session config after appending for host key : "+(session.getConfig("server_host_key")));
			logger.info("Session timeout is in : "+session.getTimeout());
			session.connect();
			if(session!=null) {
				logger.info("Session established via catch 1");
			}
			channel = session.openChannel("sftp");
			if(channel!=null) {
				logger.info("Channel established via catch 1");
			}
			sftp = (ChannelSftp) channel;
			sftp.connect();
			if(sftp!=null) {
				logger.info("sftp established via catch 1");
			}
			loggedIn = true;
			logger.error("User " + user + " successfully logged in on server " + hostName);
			cwd = sftp.pwd();
		} else {
			logger.info("Entered else block of catch 1");
			loggedIn = false;
			logger.fatal("User " + user + " failed to log in on server " + hostName);
			throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1003L, e);
		}
	} catch (JSchException ex) {
		logger.info("Entered JSCHException of block 1");
		logger.info("The exception from jsch block is "+ex.getMessage());
		loggedIn = false;
		logger.fatal("User " + user + " failed to log in on server " + hostName);
		throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1003L, ex);
	}

	catch (SftpException ex) {
		logger.info("Entered SFTPException of block 1");
		throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1020L, ex);
	} catch (SecurityException ex) {
		logger.fatal(ex);
		throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1020L, ex);
	}
} catch (SftpException e) {
	throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1020L, e);
} catch (SecurityException e) {
	logger.fatal(e);
	throw new RBException(com.j2fe.ra.fileSystem.ftp.FTP.class, 1020L, e);
}

}

public static Session getSession(JSch jsch, String host, String user, String password, int port, String proxyHost,
int proxyPort) throws JSchException {

Session session = jsch.getSession(user, host, port);
java.util.Properties config = new java.util.Properties();
logger.info("Session config for host key : "+(session.getConfig("server_host_key")));
config.put("server_host_key", "ssh-rsa,"+session.getConfig("server_host_key"));
logger.info("Session config after appending for host key : "+(config.get("server_host_key")));
config.put("StrictHostKeyChecking", "no");
config.put("PreferredAuthentications", "publickey,keyboard-interactive,password");
session.setConfig(config);
session.setTimeout(1800*1000);
if (proxyHost != null) {
	session.setProxy(new ProxySOCKS5(proxyHost, proxyPort));
}
if (password != null) {
	session.setPassword(password);
}
return session;

}

And the logs are:

Retry # 2 of method connect necessary. Problem: ERROR: Failed to login to (S)FTP Server.
Error occoured during reconnect to FTP server
Trying to log in
Entered method 1 of connect
Trying to log in on server
Block 1 user,Hostname and port are *********************************************
Entered catch of method 1
The error message in catch 1 is : Algorithm negotiation fail: algorithmName="server_host_key" jschProposal="ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256" serverProposal="ssh-rsa,ssh-dss"
Session config for host key : ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256
Session config after appending for host key : ssh-rsa,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256
Session setup done
Session config after appending for host key : ssh-rsa,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256
Session timeout is in : 1800000
Entered JSCHException of block 1
The exception from jsch block is java.net.ConnectException: Connection timed out

Kindly guide why after deploying this version i am facing this error but still after backporting the jsch jar to older version it again starts working fine.