Restrict users to use conn /as sysdba from OS Level

Oracle

To avoid a user to connecting to Database using connect /as sysdba after they log-in to OS,We can follow two methods.

1.In sqlnet.ora file modify the following line to
SQLNET.AUTHENTICATION_SERVICES=(NONE)

2.remove dba group to the user who is logging in to the system.
Note that orapwd file is used to authenticate users over the network only.users who already logged in to the system canĂ­t
be restricted to connect /as sysdba