Oracle 11.2.0.4 x64
OS CentOS 6.6 x64
问题描述：
alert日志出现网络错误如下
***********************************************************************
Fatal NI connect error 12170.
VERSION INFORMATION:
TNS for Linux: Version 11.2.0.4.0 - Production
Oracle Bequeath NT Protocol Adapter for Linux: Version 11.2.0.4.0 - Production
TCP/IP NT Protocol Adapter for Linux: Version 11.2.0.4.0 - Production
Time: 29-MAY-2018 12:03:36
Tracing not turned on.
Tns error struct:
ns main err code: 12535
TNS-12535: TNS:operation timed out
ns secondary err code: 12560
nt main err code: 505
TNS-00505: Operation timed out
nt secondary err code: 110
nt OS err code: 0
Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=10.68.196.88)(PORT=62731))
Tue May 29 12:03:45 2018
***********************************************************************
问题原因：
1、Client在default 60秒内没有完成认证
2、网络攻击，例如：半开连接攻击
3、DB负载太高
解决方案：
①sqlnet.ora文件加入SQLNET.INBOUND_CONNECT_TIMEOUT=0
To specify the time, in seconds, for a client to connect with the database server and provide the necessary authentication information.
Default 60 seconds(11.2)
②listener.ora文件加入INBOUND_CONNECT_TIMEOUT_listener_name=0
To specify the time, in seconds, for the client to complete its connect request to the listener after the network connection had been established.
Default 60 seconds(11.2)
③重载监听lsnrctl reload
参考文档：
https://www.cnblogs.com/Richardzhu/articles/2836466.html
https://docs.oracle.com/cd/E11882_01/network.112/e10835/sqlnet.htm#NETRF210 搜索SQLNET.INBOUND_CONNECT_TIMEOUT
https://docs.oracle.com/cd/E11882_01/network.112/e10835/listener.htm#NETRF312 搜索INBOUND_CONNECT_TIMEOUT_listener_name
-The End-