does Dm server make use of some ports internally .

I faced some problem when starting a RMI service within a bundle deployed in DM-server.

Outside DM when i start the service and connect remotely i am able to connect to it .But when the same service is started from within dm it refuses connection


Previously i was trying to export the object on anonymous port
Code:
UnicastRemoteObject.exportObject(engine)
It was working fine outside the dm-server but inside dm-server i had to give some firewall free port as well
Code:
UnicastRemoteObject.exportObject(engine,Integer.parseInt(FIREWALL_PORT));