tnsping遇到TNS

    从客户端tnsping 一台数据库，报错“TNS-12537:TNS:连接关闭”，奇怪~~，服务器端可以tnsping通，也可以正常访问数据库，listener状态也正常，为什么客户端连接不上，查了一下原因，为sqlnet.ora文件做了Validnode Verification 的限制。

    Information from metalink: You can configure the sqlnet.ora file to allow and deny access to the database via the validnode checking parmeters in sqlnet.ora file :TCP.VALIDNODE_CHECKING Use to specify whether to screen access to the database.Value is either YES or ON e.g.TCP.VALIDNODE_CHECKING = YES

TCP.EXCLUDED_NODES Use to specify which clients using the TCP/IP protocol are denied access to the database. Hostname and ipaddress can be usede.g.TCP.EXCLUDED_NODES= (138.3.33.33)

TCP.INVITED_NODES Use to specify which clients using the TCP/IP protocol are allowed access to the database. Hostname and ipadddress can be used. e.g.TCP.INVITED_NODES=(138.4.44.44, hammer)

Please note that without the servers hostname or ipaddress in the invitied list, then PMON will not register with the listener.Any changes to the values requires the TNS listener to be reload