It may look like it's complex but look at the code below. It achieves
everything you need without doing any low level network programming (and it
is not an easy thing to do actually).
The only thing needed is a lookup service running somewhere on the network.
Implementation of a lookup service is part of Jini Starter Kit (it's called
Reggie). The simplest thing to do is to run it on the same machine as your
server.

<code>
public interface MyServiceInterface extends Remote {
 public void myMethod() throws RemoteException;
}

public class TestServer implements MyServiceInterface {

 private final MyServiceInterface myProxy;
 private final JoinManager joinManager;

 public TestServer() throws ExportException, IOException {
   final Exporter exporter = new BasicJeriExporter(
     TcpServerEndpoint.getInstance(0), new BasicILFactory());
   myProxy = (MyServiceInterface) exporter.export(this);
   joinManager =
     new JoinManager(myProxy, null, (ServiceID)null,
       new LookupDiscovery(LookupDiscovery.ALL_GROUPS),
         new LeaseRenewalManager());
 }

 @Override
 public void myMethod() {
 }

 private synchronized void justStayAlive() throws InterruptedException {
   wait();
 }

 public static void main(String[] args) throws Exception {
   new TestServer().justStayAlive();
 }

}

public class TestClient {
 
 public static void main(String args[]) throws Exception {

   final ServiceDiscoveryManager sdm =
     new ServiceDiscoveryManager(
       new LookupDiscovery(
         LookupDiscovery.ALL_GROUPS), new LeaseRenewalManager());

   //wait forever for a server
   final ServiceItem item = sdm.lookup(
     new ServiceTemplate(
       null, new Class[] {MyServiceInterface.class}, null),
       null, Long.MAX_VALUE);

   if (item != null) {
     MyServiceInterface myService = (MyServiceInterface) item.service;
     myService.myMethod();
   }

 }

}
</code>

I had misunderstood your problem domain.

I didn't intend to mean that your problem didn't need solving. Rather that one
solution to the problem would be to shift the problem domain i.e. move it from
the domain of broadcast service location to that of a simple static network.

My assumption was that the information necessary to do this would be available,
just that you didn't happen to have it. The simple solution does require you to
be in full control of the network and for the network to be suitably configured
already. I now understand that that is not the case, so it won't work.

I hope you find a suitable method, Michal Kleczek's does look worth
investigation. I tried to follow the link he posted but the server was not
responding when I requested it.