How to audit failed login attempts in Oracle

I just copy the article from Mr Messin's blog.

You must set the audit_trail=DB in the init.ora/spfile
then you must audit with audit session whenever not successful ;
Here is a complete walk through on the setup and a script that will help query the audit trail for the failed login attempts. Be sure to clean up you audit trail so it does not grow out of control.

The Example Walk Through for Setup:

SQL> connect sys as sysdba
Enter password: ******
Connected.
SQL> alter system set audit_trail=DB scope=spfile ;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup ;
ORACLE instance started.

Total System Global Area 612368384 bytes
Fixed Size 1250428 bytes
Variable Size 234883972 bytes
Database Buffers 369098752 bytes
Redo Buffers 7135232 bytes
Database mounted.
Database opened.
SQL> audit session whenever not successful ;

Audit succeeded.

SQL> connect dummy/dummy
ERROR:
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
SQL> connect sys as sysdba
Enter password: ******
Connected.
SQL> select os_username,
username,
userhost,
to_char(timestamp,'mm/dd/yyyy hh24:mi:ss') timestamp,
returncode
from dba_audit_session
where action_name = 'LOGON'
and returncode > 0
order by timestamp ;

OS_USERNAME
--------------------------------------------------------------------------------
USERNAME
------------------------------
USERHOST
--------------------------------------------------------------------------------TIMESTAMP RETURNCODE
------------------- ----------------
MRMESSIN\Mike Messina
DUMMYWORKGROUP\MRMESSIN
11/08/2007 09:07:54 1017
SQL>

Here is a script that will show you the failed login attempts made to an Oracle Database after your setup.

-----------------------------------------------
-- see_failed_login_attempts.sql
--
-- Michael Messina
--
-- query the Oracle Audit Trail and
-- will write a log file of the failed
-- login attempts for the database.
--
-- Requires:
-- audit_trail=DB in init.ora/spfile
-- audit session whenever not successful ;
-----------------------------------------------
set pagesize 200
set linesize 150
column os_username format a15
column username format a15
column userhost format a40
column timestamp format a20
column returncode format 9999999999

spool failed_login_attempts.log

select os_username,
username,
userhost,
to_char(timestamp,'mm/dd/yyyy hh24:mi:ss') timestamp,
-- action_name,
returncode
from dba_audit_session
where action_name = 'LOGON'
and returncode > 0
order by timestamp ;

spool off