Shell.java

/**
 * This program enables you to connect to sshd server and get the shell prompt. You will be asked
 * username, hostname and passwd. If everything works fine, you will get the shell prompt. Output
 * may be ugly because of lacks of terminal-emulation, but you can issue commands.
 */
import com.jcraft.jsch.Channel;
import com.jcraft.jsch.JSch;
import com.jcraft.jsch.Session;
import com.jcraft.jsch.UIKeyboardInteractive;
import com.jcraft.jsch.UserInfo;
import javax.swing.JOptionPane;

public class Shell {
  public static void main(String[] arg) {

    try {
      JSch jsch = new JSch();

      // jsch.setKnownHosts("/home/foo/.ssh/known_hosts");

      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 session = jsch.getSession(user, host, 22);

      String passwd = JOptionPane.showInputDialog("Enter password");
      session.setPassword(passwd);

      UserInfo ui = new MyUserInfo() {
        @Override
        public void showMessage(String message) {
          JOptionPane.showMessageDialog(null, message);
        }

        @Override
        public boolean promptYesNo(String message) {
          Object[] options = {"yes", "no"};
          int foo = JOptionPane.showOptionDialog(null, message, "Warning",
              JOptionPane.DEFAULT_OPTION, JOptionPane.WARNING_MESSAGE, null, options, options[0]);
          return foo == 0;
        }

        // If password is not given before the invocation of Session#connect(),
        // implement also following methods,
        // * UserInfo#getPassword(),
        // * UserInfo#promptPassword(String message) and
        // * UIKeyboardInteractive#promptKeyboardInteractive()

      };

      session.setUserInfo(ui);

      // It must not be recommended, but if you want to skip host-key check,
      // invoke following,
      // session.setConfig("StrictHostKeyChecking", "no");

      // session.connect();
      session.connect(30000); // making a connection with timeout.

      Channel channel = session.openChannel("shell");

      // Enable agent-forwarding.
      // ((ChannelShell) channel).setAgentForwarding(true);

      channel.setInputStream(System.in);
      // a hack for MS-DOS prompt on Windows.
      // channel.setInputStream(new FilterInputStream(System.in) {
      // @Override
      // public int read(byte[] b, int off, int len) throws IOException {
      // return in.read(b, off, len > 1024 ? 1024 : len);
      // }
      // });

      channel.setOutputStream(System.out);

      // Choose the pty-type "vt102".
      // ((ChannelShell) channel).setPtyType("vt102");

      // Set environment variable "LANG" as "ja_JP.eucJP".
      // ((ChannelShell) channel).setEnv("LANG", "ja_JP.eucJP");

      // channel.connect();
      channel.connect(3 * 1000);
    } catch (Exception e) {
      System.out.println(e);
    }
  }

  public abstract static class MyUserInfo implements UserInfo, UIKeyboardInteractive {
    @Override
    public String getPassword() {
      return null;
    }

    @Override
    public String getPassphrase() {
      return null;
    }

    @Override
    public boolean promptPassphrase(String message) {
      return false;
    }

    @Override
    public boolean promptPassword(String message) {
      return false;
    }

    @Override
    public String[] promptKeyboardInteractive(String destination, String name, String instruction,
        String[] prompt, boolean[] echo) {
      return null;
    }
  }
}