How can i get ipaddress of the client machine

Question

I tried the below trigger to check the client ipaddress but
I am getting error 'identifier 'sys_context' must be declared'
Declare
     IP_ID varchar2(16);
     T_IP_ID NUMBER(15);
Begin
     select sys_context('USERENV','IP_ADDRESS') into IP_ID from dual;
     IF :EMP_NO IS NULL THEN
MESSAGE('ENTER YOUR USER_ID NOW');MESSAGE(' ');
Raise Form_Trigger_Failure;
ELSE
set_item_property('CHG_PWD',DISPLAYED,PROPERTY_TRUE);
BEGIN
SELECT USER_CATEGORY,IP_ADD INTO :GLOBAL.CAT,IP_ID from USER_ADMIN_MASTER
WHERE USER_ID = :EMP_NO AND T_IP_ID=IP_ID AND EFF_END_DATE IS NULL;
:GLOBAL.EMP := :EMP_NO;
NEXT_ITEM;
EXCEPTION
WHEN NO_DATA_FOUND THEN
BELL;
MESSAGE(TO_CHAR(:EMP_NO)||'- IS NOT A VAILD USER_ID ! PL CHECK AND RE-ENTER');
MESSAGE(' ');
RAISE FORM_TRIGGER_FAILURE;
END ;
END IF;
End;
Dev

Answer 1

I don't know, I use this in SQL*Plus script:
Try:
declare
cursor c_ctx is select
select  SYS_CONTEXT('USERENV','IP_ADDRESS') ip_address from dual:
ctx c_ctx%ROWTYPE;
IP_ID varchar2(15);
begin
   open c_ctx;
   fetch c_ctx into ctx;
   close c_ctx;
   IP_ID := ctx.ip_address;Regards