1、官方说明：
SQLNET.AUTHENTICATION_SERVICES
Purpose
Use the parameter SQLNET.AUTHENTICATION_SERVICES to enable one or more authentication services. If authentication has been installed, it is recommended that this parameter be set to either none or to one of the authentication methods.
Default
None
Values
Authentication Methods Available with Oracle Net Services:
· 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
2、测试：
可以通过对SQLNET.AUTHENTICATION_SERVICES值进行修改查看其影响。
A.SQLNET.AUTHENTICATION_SERVICES=（NTS）
B.SQLNET.AUTHENTICATION_SERVICES=（NONE）
C.SQLNET.AUTHENTICATION_SERVICES=（ALL）
D.无sqlnet.ora文件：