/**
   * Determines whether a vaild session exists for the contact of remote machine.
   *
   * @param sshContact ID of SSH Contact
   * @return <tt>true</tt> if the session is connected <tt>false</tt> otherwise
   */
  public boolean isSessionValid(ContactSSH sshContact) {
    Session sshSession = sshContact.getSSHSession();
    if (sshSession != null) if (sshSession.isConnected()) return true;

    // remove reference to an unconnected SSH Session, if any
    sshContact.setSSHSession(null);
    return false;
  }
  /**
   * Creates a SSH Session with a remote machine and tries to login according to the details
   * specified by Contact An appropriate message is shown to the end user in case the login fails
   *
   * @param sshContact ID of SSH Contact
   * @throws JSchException if a JSch is unable to create a SSH Session with the remote machine
   * @throws InterruptedException if the thread is interrupted before session connected or is timed
   *     out
   * @throws OperationFailedException if not of above reasons :-)
   */
  public void createSSHSessionAndLogin(ContactSSH sshContact)
      throws JSchException, OperationFailedException, InterruptedException {
    logger.info("Creating a new SSH Session to " + sshContact.getHostName());

    // creating a new JSch Stack identifier for contact
    JSch jsch = new JSch();

    String knownHosts = (String) accountID.getAccountProperties().get("KNOWN_HOSTS_FILE");

    if (!knownHosts.equals("Optional")) jsch.setKnownHosts(knownHosts);

    String identitiyKey = (String) accountID.getAccountProperties().get("IDENTITY_FILE");

    String userName = sshContact.getUserName();

    // use the name of system user if the contact has not supplied SSH
    // details
    if (userName.equals("")) userName = System.getProperty("user.name");

    if (!identitiyKey.equals("Optional")) jsch.addIdentity(identitiyKey);

    // creating a new session for the contact
    Session session =
        jsch.getSession(
            userName, sshContact.getHostName(), sshContact.getSSHConfigurationForm().getPort());

    /**
     * Creating and associating User Info with the session User Info passes authentication from
     * sshContact to SSH Stack
     */
    SSHUserInfo sshUserInfo = new SSHUserInfo(sshContact);

    session.setUserInfo(sshUserInfo);

    /** initializing the session */
    session.connect(connectionTimeout);

    int count = 0;

    // wait for session to get connected
    while (!session.isConnected() && count <= 30000) {
      Thread.sleep(1000);
      count += 1000;
      logger.trace("SSH:" + sshContact.getHostName() + ": Sleep zzz .. ");
    }

    // if timeout have exceeded
    if (count > 30000) {
      sshContact.setSSHSession(null);
      JOptionPane.showMessageDialog(
          null, "SSH Connection attempt to " + sshContact.getHostName() + " timed out");

      // error codes are not defined yet
      throw new OperationFailedException(
          "SSH Connection attempt to " + sshContact.getHostName() + " timed out", 2);
    }

    sshContact.setJSch(jsch);
    sshContact.setSSHSession(session);

    logger.info("A new SSH Session to " + sshContact.getHostName() + " Created");
  }