SYSTEM user's accounts get locks automatically

Question

Oracle SYSTEM user's account gets lock automatically after every 4-5 days. I user to run following query which unlocks the account:
SQL:\>ALTER USER system ACCOUNT UNLOCK;
How I can stop this happening? I am not able to alter profile for unlimited attempts also.
Is there any workout, please help me....

Answer 1

In my opinion, you should immediately find out who constantly tries to guess the password of system instead of making it possible for him to try that indefinitely without locking the account. That is like switching off the annoying alert sirene if someone constantly tries to break in.
You should
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> alter system set audit_trail=true scope=spfile;
System altered.
SQL> startup force
ORACLE instance started.
Total System Global Area  313860096 bytes
Fixed Size                  1299624 bytes
Variable Size             285215576 bytes
Database Buffers           20971520 bytes
Redo Buffers                6373376 bytes
Database mounted.
Database opened.
SQL> audit session whenever not successful;
Audit succeeded.
SQL> select count(*) from dba_audit_trail;
  COUNT(*)
         0
SQL> connect system/wrongpw@prima
ERROR:
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
SQL> connect sys/oracle@prima as sysdba
Connected.
SQL> select count(*) from dba_audit_trail;
  COUNT(*)
         1