In Oracle 10g and above, the listener is secured by default, and only user who started the listener can run the commands.
In order to set password on listener, follow the steps:
1) LSNRCTL> set current_listener
2) LSNRCTL> change_password
New password: yourpassword
Reenter new password: yourpassword
3) LSNRCTL> save_config
4) LSNRCTL> status
Now Any One Want Start Administrating Listener Will be Asked for Password , After This you can manager Your Listener .
As the another user, enter the password to administer the listener:
1) LSNRCTL> set password
2) LSNRCTL> stop