Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
[oracle@ocm1 admin]$ sqlplus bys/bys@192.168.1.211:1521/bys3
SQL*Plus: Release 10.2.0.1.0 - Production on Fri Jan 17 11:13:59 2014
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> exit
#################################################
服务端与客户端同时起作用==认证方式==>> SQLNET.AUTHENTICATION_SERVICES
有三个参数：none for no authentication methods. A valid username and password can be used to access the database.
all for all authentication methods
nts for Windows NT native authentication ---这个只对WINDOWS上有用了。
当客户端与服务端SQLNET.AUTHENTICATION_SERVICES=(ALL)无法 用AA/BB用户名密码登陆。有一边是NONE即可连接。
1.服务器端不配置SQLNET.ORA文件，在客户端配置SQLNET.AUTHENTICATION_SERVICES=(ALL)，可以正常登陆。
[oracle@ocm1 admin]$ cat sqlnet.oraNAMES.DIRECTORY_PATH=(tnsnames,ezconnect)
[oracle@ocm1 admin]$ sqlplus bys/bys@bys3
SQL*Plus: Release 10.2.0.1.0 - Production on Fri Jan 17 11:24:45 2014
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL>
2.当客户端与服务端同时配置：SQLNET.AUTHENTICATION_SERVICES=(ALL)无法用AA/BB用户名密码登陆
--接上一步实验：[oracle@bys3 admin]$ cat sqlnet.ora
SQLNET.AUTHENTICATION_SERVICES=(ALL)
从OCM1主机上测试：登陆报错：ORA-12641:
[oracle@ocm1 admin]$ sqlplus bys/bys@bys3
SQL*Plus: Release 10.2.0.1.0 - Production on Fri Jan 17 11:27:29 2014
Copyright (c) 1982, 2005, Oracle. All rights reserved.
ERROR:
ORA-12641: Authentication service failed to initialize
此时，将客户端或服务器的之一的sqlnet.ora 改为SQLNET.AUTHENTICATION_SERVICES=(NONE)，即可连接--道理同上一步实验。