How do I run SSH commands on remote system using Java?

Question

I am new to this kind of Java application and looking for some sample code on how to connect to a remote server using SSH , execute commands, and get output back using Java as programming language.

Answer 1

Have a look at Runtime.exec() Javadoc

Process p = Runtime.getRuntime().exec("ssh myhost");
PrintStream out = new PrintStream(p.getOutputStream());
BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));

out.println("ls -l /home/me");
while (in.ready()) {
  String s = in.readLine();
  System.out.println(s);
}
out.println("exit");

p.waitFor();

Answer 2

JSch is a pure Java implementation of SSH2 that helps you run commands on remote machines. You can find it here, and there are some examples here.

You can use exec.java.

Answer 3

Below is the easiest way to SSh in java. Download any of the file in the below link and extract, then add the jar file from the extracted file and add to your build path of the project http://www.ganymed.ethz.ch/ssh2/ and use the below method

public void SSHClient(String serverIp,String command, String usernameString,String password) throws IOException{
        System.out.println("inside the ssh function");
        try
        {
            Connection conn = new Connection(serverIp);
            conn.connect();
            boolean isAuthenticated = conn.authenticateWithPassword(usernameString, password);
            if (isAuthenticated == false)
                throw new IOException("Authentication failed.");        
            ch.ethz.ssh2.Session sess = conn.openSession();
            sess.execCommand(command);  
            InputStream stdout = new StreamGobbler(sess.getStdout());
            BufferedReader br = new BufferedReader(new InputStreamReader(stdout));
            System.out.println("the output of the command is");
            while (true)
            {
                String line = br.readLine();
                if (line == null)
                    break;
                System.out.println(line);
            }
            System.out.println("ExitCode: " + sess.getExitStatus());
            sess.close();
            conn.close();
        }
        catch (IOException e)
        {
            e.printStackTrace(System.err);

        }
    }

Answer 4

I created solution based on JSch library:

import com.google.common.io.CharStreams
import com.jcraft.jsch.ChannelExec
import com.jcraft.jsch.JSch
import com.jcraft.jsch.JSchException
import com.jcraft.jsch.Session

import static java.util.Arrays.asList

class RunCommandViaSsh {

    private static final String SSH_HOST = "test.domain.com"
    private static final String SSH_LOGIN = "username"
    private static final String SSH_PASSWORD = "password"

    public static void main() {
        System.out.println(runCommand("pwd"))
        System.out.println(runCommand("ls -la"));
    }

    private static List<String> runCommand(String command) {
        Session session = setupSshSession();
        session.connect();

        ChannelExec channel = (ChannelExec) session.openChannel("exec");
        try {
            channel.setCommand(command);
            channel.setInputStream(null);
            InputStream output = channel.getInputStream();
            channel.connect();

            String result = CharStreams.toString(new InputStreamReader(output));
            return asList(result.split("\n"));

        } catch (JSchException | IOException e) {
            closeConnection(channel, session)
            throw new RuntimeException(e)

        } finally {
            closeConnection(channel, session)
        }
    }

    private static Session setupSshSession() {
        Session session = new JSch().getSession(SSH_LOGIN, SSH_HOST, 22);
        session.setPassword(SSH_PASSWORD);
        session.setConfig("PreferredAuthentications", "publickey,keyboard-interactive,password");
        session.setConfig("StrictHostKeyChecking", "no"); // disable check for RSA key
        return session;
    }

    private static void closeConnection(ChannelExec channel, Session session) {
        try {
            channel.disconnect()
        } catch (Exception ignored) {
        }
        session.disconnect()
    }
}

Answer 5

You may take a look at this Java based framework for remote command execution, incl. via SSH: https://github.com/jkovacic/remote-exec It relies on two opensource SSH libraries, either JSch (for this implementation even an ECDSA authentication is supported) or Ganymed (one of these two libraries will be enough). At the first glance it might look a bit complex, you'll have to prepare plenty of SSH related classes (providing server and your user details, specifying encryption details, provide OpenSSH compatible private keys, etc., but the SSH itself is quite complex too). On the other hand, the modular design allows for simple inclusion of more SSH libraries, easy implementation of other command's output processing or even interactive classes etc.

Answer 6

I used ganymede for this a few yeas ago... http://www.cleondris.ch/opensource/ssh2/