Operating System reserves first 1024 ports for its internal usage and each port within 1024 port has been assigned for different protocols. When I say reserved it means that only Root/Administrator user can change the preferences. Here are the list of ports and their default assignments.
|8000||Oracle Applications http port|
|8100||Oracle Application PLS port|
|9000||Oracle Applications forms server port|
More default ports to come.... Keep watching......