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-- 配置sqlnet.ora 限制IP访问Oracle
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与防火墙类似的功能，Oracle 提供限制与允许特定的IP或主机名通过Oracle Net来访问数据库。这个功能由sqlnet.ora配置文件来实现。该文件通常$ORACLE_HOME/network/admin/ 目录下，与tnsnames.ora以及listener.ora位于同一路径。用法也比较简单。通过监听器的限制，实现轻量级访问限制，比在数据库内部通过触发器进行限制效率要高。
1. 实现方式
通过在sqlnet.ora文件中增加下列记录来实现
tcp.validnode_checking = yes
tcp.invited_nodes = (hostname1, hostname2，ip1,ip2)
tcp.excluded_nodes = (10.103.11.17,hostname1,hostname2)
当使用invited_nodes时，则所有没有包含在invited_nodes值中的IP或主机将无法通过Oracel Net连接到数据库。而如果使用
excluded_nodes时，除了excluded_nodes值中列出的IP和主机不可访问之外，其余的节点都可以访问数据库。通常情况下，更倾向于使
用excluded_nodes参数。
2. 注意事项
使用excluded_nodes与invited_nodes的一些特性
不支持通配符的使用(如hostname不能写为svhs0*，IP地址不能写为10.103.11.*）
excluded_nodes与invited_nodes为互斥方式，要么使用前者，要么使用后者
如果tcp.invited_nodes与tcp.excluded_nodes都存在，则tcp.invited_nodes优先
要将本地地址，或者Cluster群集其他节点的地址都加入到允许列表，否则监听器可能无法启动
修改之后，一定要重起监听或reload才能生效，而不需要重新启动数据库
仅提供对TCP/IP协议的支持
3. 实战演习
-->使用tnsping demo92，连接正常
C:>tnsping demo92
TNS Ping Utility for 32-bit Windows: Version 11.2.0.1.0 - Production on 25-JUN-2011 18:55:39
Copyright (c) 1997, 2010, Oracle. All rights reserved.
Used parameter files:
d:appRobinsonOracle_clientproduct11.2.0client_1networkadminsqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 10.103.11.20
9)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = demo92)))
OK (0 msec)
-->查看配置文件
[oracle@test admin]$ more sqlnet.ora
# SQLNET.ORA Network Configuration File: /oracle/92/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (ONAMES, TNSNAMES, HOSTNAME)
#Added by Robinson
tcp.validnode_checking = yes
tcp.excluded_nodes = (10.103.11.17)
-->重新reload
[oracle@test admin]$ lsnrctl reload listener_demo92
LSNRCTL for Linux: Version 9.2.0.8.0 - Production on 26-JUN-2011 10:03:11
Copyright (c) 1991, 2006, Oracle Corporation. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=test)(PORT=1521)))
The command completed successfully
-->再次tnsping时，收到TNS-12547错误
C:>tnsping demo92
TNS Ping Utility for 32-bit Windows: Version 11.2.0.1.0 - Production on 25-JUN-2011 19:01:21
Copyright (c) 1997, 2010, Oracle. All rights reserved.
Used parameter files:
d:appRobinsonOracle_clientproduct11.2.0client_1networkadminsqlnet.ora
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 10.103.11.20
9)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = demo92)))
TNS-12547: TNS:lost contact
-->下面的演示中如果excluded_nodes与invited_nodes都存在，则invited_nodes优先，不再演示
[oracle@test admin]$ more sqlnet.ora
# SQLNET.ORA Network Configuration File: /oracle/92/network/admin/sqlnet.ora
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (ONAMES, TNSNAMES, HOSTNAME)
#Added by Robinson
tcp.validnode_checking = yes
tcp.excluded_nodes = (10.103.11.17)
tcp.invited_nodes = (10.103.11.17)