Thanks to Matthias Wiedemann.
I used the SSH tunneling https://www.ssh.com/academy/ssh/tunneling/example as Matthias Wiedemann advised.
Total:
1 step. Connecting via SSH and create session SSH
SSH ssh = new SSH(user, password, host, port);
Session session = SSHUtil.createSession(ssh);
2 step. Creating a tunnel using SSH
SSHUtil.createChannel(session, outputConsole);
SSHUtil.createSshTunnel(session, port);
3 step. Connection via Telnet and executing Telnet commands using the tunnel port (instead of 5000, the port became 9999).
clientForTelnet = new ClientForTelnet(new Telnet(host, port));
outputConsole.print(TelnetUtil.connect(clientForTelnet));
outputConsole is PrintStream.
I got the following:
1.
public class SSHUtil{
private final static Logger LOGGER = LogManager.getLogger(SSHUtil.class);
public static Session createSession(SSH ssh) {
Session session = null;
try {
session = new JSch().getSession(ssh.getUSER(), ssh.getHOST().getIp(), ssh.getPORT().getPort());
session.setPassword(ssh.getPASSWORD());
session.setConfig("StrictHostKeyChecking", "no"); // It must not be recommended, but if you want to skip host-key check
session.connect(10000);
LOGGER.info("SSH session created");
} catch (JSchException e) {
LOGGER.error("SSH session not created " + e);
}
return session;
}
public static Channel createChannel(Session session, PrintStream output) {
Channel channel = null;
try {
channel = session.openChannel("shell");
channel.setInputStream(System.in);
channel.setOutputStream(output);
// streamOut = channel.getOutputStream();
channel.connect(10000);
LOGGER.info("SSH channel created");
} catch (JSchException e) {
LOGGER.error("SSH channel not created " + e);
}
return channel;
}
public static void createSshTunnel(Session session, Port port) {
// TODO сделать пул портов, чтобы исключить вероятность, что порт 9999 занят
try {
session.setPortForwardingL(9999, session.getHost(), port.getPort());
LOGGER.info("Tunnel created localhost:" + 9999 + " -> " + session.getHost() + ":" + port.getPort());
} catch (JSchException e) {
LOGGER.error("SSH tunnel not created " + e);
}
}
public static void disconnect(Session session) {
if (session != null && session.isConnected()) {
session.disconnect();
}
}
}
- public class TelnetUtil {
private final static Logger LOGGER = LogManager.getLogger(TelnetUtil.class);
public static String connect(ClientForTelnet clientForTelnet) {
try {
// Connect to the server
clientForTelnet.getTc().connect(clientForTelnet.getTelnet().getHOST().getIp(), clientForTelnet.getTelnet().getPORT().getPort());
// Get input and output stream references
clientForTelnet.setIn(clientForTelnet.getTc().getInputStream());
clientForTelnet.setOut(new PrintStream(clientForTelnet.getTc().getOutputStream()));
} catch (IOException e) {
LOGGER.error(e);
}
return readUntil(clientForTelnet.getPrompt(), clientForTelnet.getIn());
}
public static String readUntil(String pattern, InputStream in) {
StringBuilder sb = new StringBuilder();
try {
char lastChar = pattern.charAt(pattern.length() - 1);
boolean found = false;
char ch = (char) in.read();
while (true) {
// System.out.print(ch);
sb.append(ch);
if (ch == lastChar) {
if (sb.toString().endsWith(pattern)) {
return sb.toString();
}
}
ch = (char) in.read();
}
} catch (IOException e) {
LOGGER.error(e);
}
return sb.toString();
}
public static void write(String value, PrintStream out) {
out.println(value);
out.flush();
}
public static String sendCommand(ClientForTelnet clientForTelnet, String command) {
write(command, clientForTelnet.getOut());
return readUntil(clientForTelnet.getPrompt(), clientForTelnet.getIn());
}
public static void disconnect(TelnetClient tc) {
try {
tc.disconnect();
} catch (IOException e) {
LOGGER.error(e);
}
}
}
public class SSH {
private final String USER;
private final String PASSWORD;
private final Host HOST;
private final Port PORT;
private final Port DEFAULT_PORT = new Port(22);
public SSH(String user, String password, Host host, Port port) {
this.USER = user;
this.PASSWORD = password;
this.HOST = host;
this.PORT = port;
}
public SSH(String user, String password, Host host) {
this.USER = user;
this.PASSWORD = password;
this.HOST = host;
this.PORT = DEFAULT_PORT;
}
public String getUSER() {
return USER;
}
public String getPASSWORD() {
return PASSWORD;
}
public Host getHOST() {
return HOST;
}
public Port getPORT() {
return PORT;
}
}
public class Telnet {
private final Host HOST;
private final Port PORT;
private final Port DEFAULT_PORT = new Port(5000);
public Telnet(Host host, Port port) {
this.HOST = host;
this.PORT = port;
}
public Telnet(Host host) {
this.HOST = host;
this.PORT = DEFAULT_PORT;
}
public Host getHOST() {
return HOST;
}
public Port getPORT() {
return PORT;
}
}
public class ClientForTelnet {
private final TelnetClient TC = new TelnetClient();
private final String PROMT = ">";
private final Telnet TELNET;
private InputStream in;
private PrintStream out;
public ClientForTelnet(Telnet telnet) {
this.TELNET = telnet;
}
public InputStream getIn() {
return in;
}
public PrintStream getOut() {
return out;
}
public Telnet getTelnet() {
return TELNET;
}
public String getPrompt() {
return PROMT;
}
public TelnetClient getTc() {
return TC;
}
public void setIn(InputStream in) {
this.in = in;
}
public void setOut(PrintStream out) {
this.out = out;
}
}
public class Host {
private final static Logger LOGGER = LogManager.getLogger(Host.class);
private String ip;
public Host(String ip) {
this.ip = ip;
}
public String getIp() {
return ip;
}
}
