How to construct an ssh tunnel inside a java program

RichardSDetsch
RichardSDetsch used Ask the Experts™
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How to have a java program do the same thing as the ssh unix command (0) where the userName does not have a password associated with it?


(0) The unix command that works
 ssh -i ~/.ssh/pemFile.pem -L 8000:ec2-0-0-0-0.compute-1.amazonaws.com:8000 userName@ec2-0-0-0-0.compute-1.amazonaws.com
 


(1) The pem file
-----BEGIN RSA PRIVATE KEY-----
SOMETEXSOMETEXTALJDLAJFAJFLADSFJASDFFDA
ALDFJALFJASLDFASFDASJDLFJASLDFJAJSSDLF
-----END RSA PRIVATE KEY-----

(2) Java program that currently does not work ( i think i need a user info object or something also I do not have both a cert and key in my pem file do I need to generate one of these?)
public static void main (String args []) throws Exception {
            String pemPath = "/Users/username/.ssh/pemFile.pem";
            String ec2 = "userName@ec2-0-0-0-0.compute-1.amazonaws.com";
            SSLSocketFactory factory = null;
             factory = getSocketFactoryPEM(pemPath);
            InetAddress remote = InetAddress.getByName(ec2);
            InetAddress local = InetAddress.getByName("localhost");
            
            Socket socket = factory.createSocket(remote, 8000, local, 8000);
      }

      public static SSLSocketFactory getSocketFactoryPEM(String pemPath) throws Exception {  
            
          Security.addProvider(new BouncyCastleProvider());

          SSLContext context = SSLContext.getInstance("TLS");

          byte[] certAndKey = getBytesFromFile(new File(pemPath));

          String delimiter = "-----BEGIN RSA PRIVATE KEY-----";
          String[] tokens = new String(certAndKey).split(delimiter);

          byte[] certBytes = tokens[0].concat(delimiter).getBytes();
          //byte[] keyBytes = tokens[1].getBytes();

          PEMReader reader;

          reader = new PEMReader(new InputStreamReader(new ByteArrayInputStream(certBytes)));
          X509Certificate cert = (X509Certificate)reader.readObject();        

          //reader = new PEMReader(new InputStreamReader(new ByteArrayInputStream(keyBytes)));
          //PrivateKey key = (PrivateKey)reader.readObject();        

          KeyStore keystore = KeyStore.getInstance("JKS");
          keystore.load(null);
          keystore.setCertificateEntry("cert-alias", cert);
          //keystore.setKeyEntry("key-alias", key, "changeit".toCharArray(), new Certificate[] {cert});

          KeyManagerFactory kmf = KeyManagerFactory.getInstance("SunX509");
          kmf.init(keystore, "changeit".toCharArray());

          KeyManager[] km = kmf.getKeyManagers();

          context.init(km, null, null);

          return context.getSocketFactory();
      }
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Tomas Helgi JohannssonDatabase Administrator / Software Engineer

Commented:
Hi!

Here are some examples to look at
http://www.example-code.com/java/ssh.asp
http://www.beanizer.org/site/index.php/en/Articles/Java-ssh-tunneling-with-jsch.html

Hope this helps.

Regards,
    Tomas Helgi
Thanks for the links they are helpful.  I will try them tonight.

Here are some of my thoughts before though.

A. The JSCH does not show me what to do with the pem file and also I do not know what to put in the userInfo object, note the unix command (0) above does not require any user input after running. If there is a command in JSCH like I see "addIdentity" what format should I give my pem file do I have to trim the -----BEGIN RSA PRIVATE KEY----- and make it byte array form.

B. If I do privKey = key.loadText("myPrivateKey.pem"); can I just give it my pem the way it is.  For the below how can I verify that a public key is in the remote ~/.ssh directory and if it is not there can I generate it from the pem file?  Does it have to exist for my unix command (0) to work?

//  Authenticate with the SSH server using the login and
    //  private key.  (The corresponding public key should've
    //  been installed on the SSH server beforehand.)
    success = ssh.AuthenticatePk("myLogin",key);
    if (success != true) {
        System.out.println(ssh.lastErrorText());
        return;
    }

Thanks, Shane
CompTIA Security+

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Top Expert 2016

Commented:
For the below how can I verify that a public key is in the remote ~/.ssh directory
If it's not there how would this work?
(0) The unix command that works
Tomas Helgi JohannssonDatabase Administrator / Software Engineer

Commented:
You will have to upload your keys to the remote server and put it into the .ssh directory for the ssh connection to work to that server.

Regards,
    Tomas Helgi
Top Expert 2016

Commented:
You will have to upload your keys to the remote server and put it into the .ssh directory
That's already done (see my last comment)

In fact, it's conceivable you might have to do the reverse if you're using Jsch, as the load methods for keys seem to want to work only with a pair of files

Author

Commented:
Thanks the below works and was derived form http://stackoverflow.com/questions/7525679/how-to-get-the-java-security-privatekey-object-from-rsa-privatekey-pem-from-a-f

public static void main (String args []) throws Exception {
            String pemPath = "/Users/userName/.ssh/pemFile.pem";
            String ec2 = "ec2-xxxxxxxx-.compute-1.amazonaws.com";
            Session session = connect(ec2, pemPath);
            session.connect();
          Thread.sleep(60000);
            session.disconnect();
}
     
       public static Session connect(String dnsName, String privKey) throws IOException {
                JSch jSch = new JSch();

                Session session = null;
                try {
                    jSch.addIdentity(privKey);
                    session = jSch.getSession("someUser", dnsName, 22);
                    java.util.Properties config = new java.util.Properties();
                    config.put("StrictHostKeyChecking", "no");
                    session.setConfig(config);
                    System.out.println("Connecting SSH to " + dnsName + " - Please wait for few minutes... ");
                    System.out.println("Forwarding");
                        int assinged_port = session.setPortForwardingL(80, dnsName, 80);
                        System.out.println("localhost:"+assinged_port+" -> "+dnsName+":80");

                } catch (JSchException e) {
                    e.printStackTrace();
                }
                  return session;

            }

Author

Commented:
Thanks the below works and was derived form http://stackoverflow.com/questions/7525679/how-to-get-the-java-security-privatekey-object-from-rsa-privatekey-pem-from-a-f

public static void main (String args []) throws Exception {
            String pemPath = "/Users/userName/.ssh/pemFile.pem";
            String ec2 = "ec2-xxxxxxxx-.compute-1.amazonaws.com";
            Session session = connect(ec2, pemPath);
            session.connect();
          Thread.sleep(60000);
            session.disconnect();
}
      
       public static Session connect(String dnsName, String privKey) throws IOException {
                JSch jSch = new JSch();

                Session session = null;
                try {
                    jSch.addIdentity(privKey);
                    session = jSch.getSession("scbeCoreDevUsEast1", dnsName, 22);
                    java.util.Properties config = new java.util.Properties();
                    config.put("StrictHostKeyChecking", "no");
                    session.setConfig(config);
                    System.out.println("Connecting SSH to " + dnsName + " - Please wait for few minutes... ");
                    System.out.println("Forwarding");
                        int assinged_port = session.setPortForwardingL(8081, dnsName, 8080);
                        System.out.println("localhost:"+assinged_port+" -> "+dnsName+":8080");

                } catch (JSchException e) {
                    e.printStackTrace();
                }
                  return session;

            }

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