ADMIN_RESTRICTIONS_listener_name=on

Setting ADMIN_RESTRICTIONS_listener_name=on disables the runtime
modification of parameters in listener.ora.
That is, the listener will refuse to accept SET commands that alter its parameters.
To change any of the parameters in listener.ora, including ADMIN_RESTRICTIONS_listener_name itself, modify the listener.ora file manually and reload its parameters (with the RELOAD
command) for the new changes to take effect without explicitly stopping and
restarting the listener.

The parameter is useful if the listener is not
password-protected.