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Implementing SSH shell terminal in webapp using JSch

I am trying to implement a shell terminal in a webapp using websocket in spring. I am able to send a single command to the JSch "exec" channel and send the output back to the websocket.
The problem I am having is:
I am not able to retain the state of the shell like working directory, when I send a second command. How can I retain the previous state? I have tried using the same session but it does not work.
public String sendCommand(String command) {
StringBuilder outputBuffer = new StringBuilder();
try {
Channel channel = sesConnection.openChannel("exec");
((ChannelExec) channel).setCommand(command);
InputStream commandOutput = channel.getInputStream();
channel.connect();
int readByte = commandOutput.read();
while (readByte != 0xffffffff) {
outputBuffer.append((char) readByte);
readByte = commandOutput.read();
}
channel.disconnect();
} catch (IOException ioX) {
logWarning(ioX.getMessage());
return null;
} catch (JSchException jschX) {
logWarning(jschX.getMessage());
return null;
}
return outputBuffer.toString();
}
To send back to the websocket, in the controller I have :
private SSHManager getSSHInstance() {
String errorMessage = null;
if (sshInstance == null) {
sshInstance = new SSHManager(username, password, host, "", port);
errorMessage = sshInstance.connect();
System.out.println("Instance created");
if (errorMessage != null) {
throw new RuntimeException("Could not create an ssh connection");
}
}
System.out.println("Returning created instance");
return sshInstance;
}
#MessageMapping("/user")
#SendTo("/topic/user")
public UserResponse getResponse(String command) {
SSHManager currInstance = getSSHInstance();
String result = currInstance.sendCommand(command);
return new UserResponse(result);
}
I tried using the "shell" channel instead of "exec" which worked for getting the input and output through standard input and output stream but I could not get the real-time input and output from/back to the websocket and UI. I am not sure how to proceed from here. Any direction on where/what to look would be very helpful.
Here is my code for the SSH terminal through standard input/output stream:
import com.jcraft.jsch.*;
public class Terminal{
public static void main(String[] args){
try{
JSch jsch=new JSch();
String host = "127.0.0.1";
String user = "user";
String password = "pass";
Session session=jsch.getSession(user, host, 5679);
session.setPassword(password);
session.setConfig("StrictHostKeyChecking", "no");
session.connect(10000);
Channel channel=session.openChannel("shell");
channel.setInputStream(System.in);
channel.setOutputStream(System.out);
channel.connect(3*1000);
}
catch(Exception e){
System.out.println(e.getMessage());
}
}
}
To send the command from the UI, I have the following:
function sendCommand() {
if (stompClient != null) {
stompClient.send("/app/user", {}, JSON.stringify({'command': $("#command").val()}));
}
}

If you want to implement an interactive shell, you have to use the "shell" channel, not the "exec" channel. The "exec" channel is intended for automating individual commands.
Some references:
What is the difference between the 'shell' channel and the 'exec' channel in JSch
JSch Shell.java example

how to set password for ssh connection in java

I want to connect my unix server using java code. first it will connect to my server location. inside that it'll connect to my server name. but at that time it'll ask for confirmation (yes/no) and password I don't know how to do?
Here's my code that I have done.please help me out on this
public static void main (String args[]) {
String user = "user";
String password = "password";
String host = "hostName";
int port=22;
//String remoteFile="/home/john/test.txt";
//String yes="yes";
try {
JSch jsch = new JSch();
Session session = jsch.getSession(user, host, port);
session.setPassword(password);
session.setConfig("StrictHostKeyChecking", "no");
System.out.println("Establishing Connection...");
session.connect();
Channel channel = session.openChannel("exec");
// After this it'll ask for confirmation and password
((ChannelExec)channel).setCommand("ssh myServerName");
channel.connect();
InputStream output = channel.getInputStream();
System.out.println("aafter stream");
int readByte = output.read();
StringBuilder outputBuffer = new StringBuilder();
while (readByte != 0xffffffff) {
//System.out.println("read byte" + readByte);
outputBuffer.append((char)readByte);
readByte = output.read();
}
System.out.println(outputBuffer.toString());
channel.disconnect();
} catch (Exception e){
System.err.print("error message" + e);
}
}

You need to get the OutputStream of JSch secured channel and insert the password in it.
Channel channel = session.openChannel("exec");
((ChannelExec) channel).setCommand("sudo -S -p '' " + command);
channel.setInputStream(null);
OutputStream out = channel.getOutputStream();
((ChannelExec) channel).setErrStream(System.err);
InputStream in = channel.getInputStream();
((ChannelExec) channel).setPty(true);
channel.connect();
out.write((password + "\n").getBytes());
out.flush();
Complete source code here: http://codeflex.co/java-run-sudo-command-on-remote-linux-host/

try {
session = jsch.getSession(user, host, port);
}
catch (JSchException e) {
throw new TransferException("Failed to open session - " + params, e);
}
session.setPassword(password);
// Create UserInfo instance in order to support SFTP connection to any machine
// without a key username and password will be given via UserInfo interface.
UserInfo userInfo = new SftpUserInfo();
session.setUserInfo(userInfo);
try {
session.connect(connectTimeout);
}
catch (JSchException e) {
throw new TransferException("Failed to connect to session - " + params, e);
}
boolean isSessionConnected = session.isConnected();
Set the password programmatically like seen above.

java jsch su- root (how can i?)

I want to connect a Linux server and execute a command, but when I send the command sh and su - it requires password, but my program sends password just before it asks. How can i solve this problem?
public class Stream
{
public void getStream(String fileName)
{
String user = usernametext.getText();
String host = hostiptext.getText();
String password = pass.getText();
String command4 = "sh\nsu -\nmypassword\n";
try
{
System.out.println("preparing the host information for stream.");
JSch jsch = new JSch();
Session session = jsch.getSession(user, host, 22);
session.setPassword(password);
session.setConfig("StrictHostKeyChecking", "no");
session.connect(10 * 1000);
Channel channel = session.openChannel("shell");
InputStream is = new ByteArrayInputStream(command4.getBytes());
channel.setInputStream(is);
channel.setOutputStream(System.out);
channel.connect(15 * 1000);
session.connect(10 * 10);
channel.disconnect();
session.disconnect();
}
catch (Exception ex)
{
System.out.println("Exception found while streaming.");
}
}
}

As you are using a shell channel why do you need to call another sh?
Any how I do the above is to pass individual command and then read the inputStream until you get back to the prompt and then you can set the next input e.g. the password or what ever.
Pseudo-code being
write "su -"
readUntil "password:"
write "******"
readUntil prompt
etc.

Multiple commands using JSch

My requirement is as follow:
I have to login to Unix box using my credentials and once login, I have to do sudo to different user. Once sudo is successful, I have to invoke shell in nohup. On completion of executions, close channel and session both.
I tried the first step which is connect using sudo command, but I don't know how to invoke shell script after the sudo command.
In the below code I am able to execute sudo command, but after getting sudo access how can I execute a shell in nohup with user masteruser. So that required files created my shell has owner as masteruser.
public class SSHUploader {
Session session = null;
public SSHUploader(){
}
public void connect(){
try {
JSch jsch = new JSch();
session = jsch.getSession("user", "xxx.xxx.xx.xx", 22);
session.setPassword("test");
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.connect();
} catch (Exception ex) {
ex.printStackTrace();
}
}
public void executeCommand(String script) throws JSchException, IOException{
System.out.println("Execute sudo");
String sudo_pass = "test";
ChannelExec channel = (ChannelExec) session.openChannel("exec");
((ChannelExec) channel).setCommand( script);
InputStream in = channel.getInputStream();
OutputStream out = channel.getOutputStream();
((ChannelExec) channel).setErrStream(System.err);
channel.connect();
out.write((sudo_pass + "\n").getBytes());
out.flush();
byte[] tmp = new byte[1024];
while (true) {
while (in.available() > 0) {
int i = in.read(tmp, 0, 1024);
if (i < 0)
break;
System.out.print(new String(tmp, 0, i));
}
if (channel.isClosed()) {
System.out.println("exit-status: " + channel.getExitStatus());
break;
}
try {
Thread.sleep(1000);
} catch (Exception ee) {
System.out.println(ee);
}
}
channel.disconnect();
System.out.println("Sudo disconnect");
}
public void disconnect(){
session.disconnect();
}
public static void main(String... args) throws JSchException, IOException {
SSHUploader up = new SSHUploader();
up.connect();
up.executeCommand("sudo -u masteruser bash");
up.disconnect();
}
}

For executing multiple commands in sequence, you can create a command string like below:
String script ="pbrun su - user; cd /home/scripts;./sample_script.sh”
Execute it and pass this string to your method above.

The post may be old, but I found another easy way that allows you to retrieve the output of each command separately. Note that this code has to be executed once the session has been opened, as shown in the examples (http://www.jcraft.com/jsch/examples/Exec.java.html):
for (String command : commands) {
ChannelExec channel = (ChannelExec) session.openChannel("exec");
channel.setInputStream(null);
channel.setErrStream(System.err);
channel.setCommand(command);
channel.connect();
printOutput(channel);
channel.disconnect();
}
Where printOutput uses channel.getInputStream() to read the result of the command.

Another solution which I find elegant is to use connection from type shell instead of exec.
But you will need to wait for the correct prompt to appear after each command like shown in the following example:
public static void main(String[] args) throws Exception{
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
Session session = null;
ChannelShell channel = null;
try {
JSch jsch = new JSch();
session = jsch.getSession("username", "192.168.1.1", 22);
session.setConfig(config);
session.setPassword("password");
session.connect();
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
channel = (ChannelShell) session.openChannel("shell");
channel.setOutputStream(outputStream);
PrintStream stream = new PrintStream(channel.getOutputStream());
channel.connect();
stream.println("touch delme.txt");
stream.flush();
String response = waitForPrompt(outputStream, "$");
System.out.println(response);
stream.println("sudo chown root delme.txt");
stream.flush();
response = waitForPrompt(outputStream, ":");
System.out.println(response);
stream.println("mysecretrootpassword");
stream.flush();
response = waitForPrompt(outputStream, "$");
System.out.println(response);
stream.println("ls -la delme.txt");
stream.flush();
response = waitForPrompt(outputStream, "$");
System.out.println(response);
} finally {
if (channel != null) {
channel.disconnect();
}
if (session != null) {
session.disconnect();
}
}
}
static public String waitForPrompt(ByteArrayOutputStream outputStream, String prompt) throws Exception {
int retries = NUMBER_OF_RETRIES;
for (int x = 1; x < retries; x++) {
TimeUnit.SECONDS.sleep(1);
if (outputStream.toString().indexOf(prompt) > 0) {
String responseString = outputStream.toString();
outputStream.reset();
return responseString;
}
}
throw new Exception("Prompt failed to show after specified timeout");
}

Jsch - Exit after Shell Script Execution

I'm trying to write a Java Program using Jsch where in I want to start the execution of a shell script using the program and exit the program once the execution of the shell script has been completed.
String userName = "";
String hostName = "";
String password = "";
JSch javaSecureChannel = new JSch();
Session jschSession = null;
Channel jschChannel = null;
try {
jschSession = javaSecureChannel.getSession(userName, hostName, 22);
Properties configurationProperties = new Properties();
configurationProperties.put("StrictHostKeyChecking", "no");
jschSession.setConfig(configurationProperties);
jschSession.setPassword(password);
jschSession.connect();
jschChannel = null;
jschChannel = jschSession.openChannel("shell");
jschChannel.setOutputStream(System.out);
File shellScript = createShellScript();
FileInputStream fin = new FileInputStream(shellScript);
byte fileContent[] = new byte[(int) shellScript.length()];
fin.read(fileContent);
InputStream in = new ByteArrayInputStream(fileContent);
jschChannel.setInputStream(in);
jschChannel.connect();
while(true){
//if(jschChannel.isClosed)
if(jschChannel.getExitStatus() == 0){
System.out.println("exit-status: " + jschChannel.getExitStatus());
break;
}
try{
Thread.sleep(1000);
}catch(Exception ee){
ee.printStackTrace();
}
}
} catch (Exception e) {
e.printStackTrace();
}
jschChannel.disconnect();
jschSession.disconnect();
System.out.println("Done...!!!");
createShellScript method is as follows.
String temporaryShellFileName = "shellscript.sh";
File fileStream = new File(temporaryShellFileName);
try {
PrintStream outStream = new PrintStream(new FileOutputStream(fileStream));
outStream.println("#!/bin/bash");
outStream.println("cd /u01/app/java/gids4x/Test");
outStream.println("Test_with_NULL.sh");
outStream.close();
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
Using the above code, I'm able to start the execution of the shell script. However, I'm not bale to terminate the program execution even after the execution of the program is completed i.e. after the execution of the Script completes.
Can you please suggest what needs to be done exactly?

I also faced the same issue and resolved it by using below two steps :
1. Sending last command as "exit"
2. Putting my mail thread sleep until channel is open
Please find the code as below :
public static void main(String[] arg){
Channel channel=null;
Session session=null;
try{
JSch.setLogger(new MyLogger());
JSch jsch=new JSch();
jsch.addIdentity("C:\\testLinuxKey.key");
String host=null;
if(arg.length>0){
host=arg[0];
}
else{
host=JOptionPane.showInputDialog("Enter username#hostname",
System.getProperty("user.name")+
"#localhost");
}
String user=host.substring(0, host.indexOf('#'));
host=host.substring(host.indexOf('#')+1);
session=jsch.getSession(user, host, 22);
// username and password will be given via UserInfo interface.
UserInfo ui=new MyUserInfo();
session.setUserInfo(ui);
session.connect();
channel=session.openChannel("shell");
//channel.setInputStream(System.in);
channel.setOutputStream(System.out);
String temporaryShellFileName = "shellscript.sh";
File fileStream = new File(temporaryShellFileName);
try {
PrintStream outStream = new PrintStream(new FileOutputStream(fileStream));
outStream.println("id");
outStream.println("sudo bash");
outStream.println("cd /tmp/");
outStream.println("/tmp/wasinfo.sh");
outStream.println("exit");
outStream.println("exit");
outStream.close();
FileInputStream fin = new FileInputStream(fileStream);
byte fileContent[] = new byte[(int) fileStream.length()];
fin.read(fileContent);
InputStream in = new ByteArrayInputStream(fileContent);
channel.setInputStream(in);
} catch (Exception e) {
System.err.println("Error: " + e.getMessage());
}
channel.connect();
while(channel.isConnected())
{
System.out.println("----- Channel On ----");
Thread.currentThread().sleep(5000);
}
channel.disconnect();
session.disconnect();
}
catch(Exception e){
System.out.println(e);
channel.disconnect();
session.disconnect();
}
System.out.println("Main End");
}

I had a similar problem. I was running a shell in a window but couldn't get Java to terminate when the window was closed. I solved it by closing the input stream.