A lot of failed login attempts in the last 30 minutes

Oracle Enterprise manager shows errors:

A lot of failed login attempts in the last 30 minutes

Checking:

select USERNAME, ACTION_NAME, RETURNCODE, count(*)
   from DBA_AUDIT_SESSION
  where TIMESTAMP > (sysdate - 2 / 24)
    and RETURNCODE != 0
  group by USERNAME, ACTION_NAME, RETURNCODE
  order by count(*);

USERNAME                       ACTION_NAME                  RETURNCODE
------------------------------ ---------------------------- ----------
  COUNT(*)
----------
MGMT_VIEW                      LOGON                             28000
        12

return code is 28000, this mean : ora-2800: the account is locked.
tet's check :

select USERNAME, PASSWORD_VERSIONS,account_status  from dba_users where username='MGMT_VIEW';

USERNAME                       PASSWORD ACCOUNT_STATUS
------------------------------ -------- --------------------------------
MGMT_VIEW                      10G 11G  LOCKED(TIMED)

In 11g, by default the password expired time is set to 180 days(in 10g it is unlimited).

select * from dba_profiles WHERE RESOURCE_NAME='PASSWORD_LIFE_TIME';
PROFILE                        RESOURCE_NAME                    RESOURCE LIMIT
------------------------------ -------------------------------- -------- -----
DEFAULT                        PASSWORD_LIFE_TIME               PASSWORD  180

Ok, let's correct this:

ALTER PROFILE DEFAULT limit  PASSWORD_LIFE_TIME UNLIMITED;

profile altered.

select * from dba_profiles WHERE RESOURCE_NAME='PASSWORD_LIFE_TIME';
PROFILE                        RESOURCE_NAME                    RESOURCE LIMIT
------------------------------ -------------------------------- -------- -----
DEFAULT                        PASSWORD_LIFE_TIME               PASSWORD  UNLIMITED

This account which already in LOCKED status didn't back to normal auto. We need to do below:

alter user MGMT_VIEW account unlock;

User altered.

select USERNAME, PASSWORD_VERSIONS,account_status  from dba_users where username='MGMT_VIEW';

USERNAME                       PASSWORD ACCOUNT_STATUS
------------------------------ -------- --------------------------------
MGMT_VIEW                      10G 11G  OPEN

that's all. Thank you ;)