Guide 2: Step-by-Step for Telnet Service JAAS Example (2)


The Telnet Service is a library that provides easy-to-integrate TELNET functionality to Java(TM) applications. Althrough its main purpose is to integrate servers as an administration console, its versatility puts creativity as the only limitation to its usage.


This example is based on 'Example 1: Telnet Service Core Simple Example Step-by-Step' and extends its functionality by adding JAAS authentication (using the telnetservice-jaas library).

The following sections show the basics of this integration activity using a simple (trivial) example.

Steps To Add JAAS Support to Your Telnet Service Enabled Application

JAAS provides a pluggable interface allowing applications to be independent from the underlying authentication system.

In our first example, we did not integrate with an application server and therefore we do not have an underlying authentication framework. To get around this, the second part of this guide will implement a very simple, hard-coded, single-user authentication, and then configure the java security framework to use it.

Notice that this example depends on the telnetservice-example1-core project, if you're using maven as a build tool, then you must run mvn install on that project to have it in your local repository; another option would be to include one of the many repositories that mirror maven artifact deployments to your project pom.

Register the JAAS extension

It is easy to add the JAAS extension to our code; Example2 will extend Example1 and overload its initialize() method to register this extension. [ ]

public class Example2 extends Example1
    public void initialize() {
        super.telnetService.registerExtension(new TelnetServiceExtensionJAASImpl());
    public static void main(String[] args) throws TelnetServiceStartException {
        Example2 example = new Example2();

That's it! If we were integrating on a framework that already provides JAAS, we would have been done! In our case, we'll include a simple LoginModule copyright of Sun Microsystems, Inc that was slightly modified for our needs.

Including a JAAS LoginModule

We won't go into the details of writing a LoginModule and its related classes, there are many good tutorials on the net for that. Look at the sources if you are curious ;-) They're here: [Sources ]

If you're running on a framework check its documentation on how to setup and enable its LoginModule configuration, the telnet service JAAS implementation looks for the login module associated with TelnetService .

Let's configure the SampleLoginModule and try the example. For that we need to:

  • edit the configuration file which is located under the ./lib/security/ , and uncomment the login.config.url that points the to login config in the user home:
    # Default login configuration file
  • then we create a .java.login.config file in the user home:
    TelnetService {
       fr.gedeon.telnetservice.jaasexample2.simplejaas.SampleLoginModule required debug=true;

    which points to the SampleLoginModule we have included. The 'debug=true' is set there temporarly to get feedback on what's going on, remove it when you know it's working as expected.

    Let's try it with its only valid credentials: username='user', password='pass':

    user name: user
    user> help
    help: display this help message
    sayhello: meet and greet
    exit: exit this session
    shutdown: shutdown the server
    user> sayhello Jojo
    Hello, Jojo!

Download the Example Source

The complete example sources can be downloaded at the project download section .

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