SQL> conn sys@orcl as sysdba
Enter password:
Connected.
SQL> drop user test cascade;

User dropped.

SQL> create user test identified by test;

User created.

SQL> grant create session to test;

Grant succeeded.

[B]SQL>-- CURRENT SQLNET.ORA ####SQLNET.AUTHENTICATION_SERVICES= (NTS)###[/B]

SQL> conn test@orcl as sysdba

Enter password:
Connected.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  171966464 bytes
Fixed Size                   787988 bytes
Variable Size             145488364 bytes
Database Buffers           25165824 bytes
Redo Buffers                 524288 bytes
Database mounted.
Database opened.
SQL> conn test/test@orcl
Connected.
SQL> shutdown
ORA-01031: insufficient privileges
SQL> desc session_privs
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------

 PRIVILEGE                                 NOT NULL VARCHAR2(40)

SQL> select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION

SQL> conn test@orcl as sysdba
Enter password:
Connected.
SQL> select * from session_privs;

PRIVILEGE
----------------------------------------
ALTER SYSTEM
AUDIT SYSTEM
CREATE SESSION

...

SQL> EXIT
Disconnected from Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - Pr
oduction
With the Partitioning, OLAP and Data Mining options
[b] change sqlnet.ora file 
SQLNET.AUTHENTICATION_SERVICES= (NONE)[/b]

C:\>net stop oracleserviceorcl
The OracleServiceORCL service is stopping........
The OracleServiceORCL service was stopped successfully.


C:\>net start oracleserviceorcl
The OracleServiceORCL service is starting........
The OracleServiceORCL service was started successfully.


C:\>sqlplus/nolog

SQL*Plus: Release 10.1.0.2.0 - Production on Mon Nov 13 16:23:23 2006

Copyright (c) 1982, 2004, Oracle.  All rights reserved.

SQL> conn test@orcl as sysdba
Enter password:
ERROR:
ORA-01031: insufficient privileges

SQL> conn test@orcl
Enter password:
Connected.
SQL> select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION

SQL> conn sys@orcl as sysdba
Enter password:
Connected.
SQL>