memorize

CREATE OR REPLACE TRIGGER authorize_users_trig
AFTER LOGON ON DATABASE

-- Description: This trigger helps database administrators to
-- control users logging into the database using various client
-- tools and machines. List of USERNAME, OSUSER, PROGRAM and
-- MACHINE entered in table AUTHORIZE_USERS_TAB will only be
-- permitted to login into the database.
-- Ref Oracle Bug No.2628258 and Doc No.2628258.8 in Metalink for
-- using RTRIM(machine,CHR(0)) in the below code.
-- Caveat: When a user tries to connect via SQL*Plus and if the
-- trigger refuses connection, info about that session is shown
-- as INACTIVE in V$SESSION, unless that user closes the SQL*Plus
-- window/session.

DECLARE
p_count NUMBER(1);
BEGIN
SELECT COUNT(*)
INTO p_count
FROM sys.authorize_users_tab
WHERE UPPER(username || osuser || program || RTRIM(machine, CHR(0))) IN
(SELECT UPPER(username || osuser || program ||
RTRIM(machine, CHR(0)))
FROM v$session !
WHERE au dsid = USERENV('sessionid')
AND logon_time =
(SELECT MAX(logon_time)
FROM v$session
WHERE audsid = USERENV('sessionid')));
IF p_count = 0 THEN
RAISE_APPLICATION_ERROR(-20001, '---> Sorry, Access Denied <---');
END IF;
END;
-----------------------------
Ask Tom variant

create or replace trigger trg_no_sys_logon
after logon
on database
declare
v_machine varchar2(30);
v_count number;
begin
    select count(machine) into v_count
    from host_machine_list
    where SYS_CONTEXT('USERENV','HOST') = MACHINE;
      If v_count = 0 then
       for check_users in(select username
                           from v$session
                           where AUDSID = USERENV('SESSIONID')) loop
         if upper(check_users.username) in ('SYSTEM')
        then
               insert into gdemo.dbas_aud3
               (
                 LOGON_TIME
                ,TERMINAL
                ,SESSIONID
                ,INSTANCE
                ,ENTRYID
                ,ISDBA
                ,CURRENT_USER
                ,CURRENT_USERID
                ,SESSION_USER
                ,SESSION_USERID
                ,PROXY_USER
                ,PROXY_USERID
                ,DB_NAME
                ,HOST
                ,OS_USER
                ,EXTERNAL_NAME
                ,IP_ADDRESS
                ,NETWORK_PROTOCOL
                ,AUTHENTICATION_TYPE)
               select
                 SYSDATE
                ,SYS_CONTEXT('USERENV','TERMINAL') TERMINAL
                ,SYS_CONTEXT('USERENV','SESSIONID') SESSIONID
                ,SYS_CONTEXT('USERENV','INSTANCE') INSTANCE
                ,SYS_CONTEXT('USERENV','ENTRYID') ENTRYID
                ,SYS_CONTEXT('USERENV','ISDBA') ISDBA
                ,SYS_CONTEXT('USERENV','CURRENT_USER') CURRENT_USER
                ,SYS_CONTEXT('USERENV','CURRENT_USERID') CURRENT_USERID
                ,SYS_CONTEXT('USERENV','SESSION_USER') SESSION_USER
                ,SYS_CONTEXT('USERENV','SESSION_USERID') SESSION_USERID
                ,SYS_CONTEXT('USERENV','PROXY_USER') PROXY_USER
                ,SYS_CONTEXT('USERENV','PROXY_USERID') PROXY_USERID
                ,SYS_CONTEXT('USERENV','DB_NAME') DB_NAME
                ,SYS_CONTEXT('USERENV','HOST') HOST
                ,SYS_CONTEXT('USERENV','OS_USER') OS_USER
                ,SYS_CONTEXT('USERENV','EXTERNAL_NAME') EXTERNAL_NAME
                ,SYS_CONTEXT('USERENV','IP_ADDRESS') IP_ADDRESS
                ,SYS_CONTEXT('USERENV','NETWORK_PROTOCOL') NETWORK_PROTOCOL
                ,SYS_CONTEXT('USERENV','AUTHENTICATION_TYPE') AUTHENTICATION_TYPE from
dual;
        end if;
        commit;
      end loop;
      END IF;
exception
 when others then
 NULL;
end trg_no_sys_logon_3;