在进行Oracle数据库巡检中常常在日志中发现这样的错误日志，但是却通常不会影响客户使用。
整体报错如下：
*********************************************************************** 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: 30-JUN-2020 09:59:59 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通过查看官方文档说明：
ORA-12170: TNS:Connect timeout occurred
Cause: The client failed to establish a connection and complete authentication in the time specified by the SQLNET.INBOUND_CONNECT_TIMEOUT parameter in the sqlnet.ora file. This error may be a result of network or system delays, or it may indicate that a malicious client is trying to cause a denial-of-service attack on the database server.这个意思是：
TNS连接超时
原因是客户端无法在指定的时间内建立连接并完成身份验证SQLNET.INBOUND_CONNECT_超时中的参数sqlnet.ora文件。此错误可能是由于网络或系统延迟造成的，也可能表示恶意客户端正试图对数据库服务器造成拒绝服务攻击。
从最终的结果数据库还可以正常使用来看，这是出现了延迟造成的。根据网上的相关错误处理办法。由于在Automatic Diagnostic Repository中的 Oracle Net diagnostic是开启状态，从而对连接延迟错误进行获取并且将其写入告警日志。解决的办法就是将自动诊断关于网络诊断的配置关闭即可。
其实整个报错这个问题并没有什么影响，如果没有特殊需求可以不关闭。
参考网络上解决方式：
【解决方式】
[oracle@node1 ~]$ lsnrctl status
LSNRCTL for Linux: Version 11.2.0.1.0 - Production on 02-MAR-2015 12:34:22
Copyright (c) 1991, 2009, Oracle. All rights reserved.
Connecting to (ADDRESS=(PROTOCOL=tcp)(HOST=)(PORT=1521))
STATUS of the LISTENER
------------------------
Alias LISTENER
Version TNSLSNR for Linux: Version 11.2.0.1.0 - Production
Start Date 02-MAR-2015 09:45:49
Uptime 0 days 2 hr. 48 min. 33 sec
Trace Level off
Security ON: Local OS Authentication
SNMP OFF
Listener Parameter File /u01/11.2.0/grid/network/admin/listener.ora
Listener Log File /u01/app/oracle/diag/tnslsnr/node1/listener/alert/log.xml
Listening Endpoints Summary...
(DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=LISTENER)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.53.105.20)(PORT=1521)))
(DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.53.105.24)(PORT=1521)))
Services Summary...
Service "+ASM" has 1 instance(s).
Instance "+ASM1", status READY, has 1 handler(s) for this service...
Service "xcky" has 1 instance(s).
Instance "xcky1", status READY, has 1 handler(s) for this service...
Service "xckyXDB" has 1 instance(s).
Instance "xcky1", status READY, has 1 handler(s) for this service...
The command completed successfully
[oracle@node1 ~]$ cd /u01/11.2.0/grid/network/admin/
[oracle@node1 admin]$ ls
endpoints_listener.ora listener.ora samples sqlnet.ora
listener1410255PM1539.bak listener.ora.bak.node1 shrept.lst
[root@node1 admin]# chmod 775 listener.ora
[root@node1 admin]# chmod 775 sqlnet.ora
--确认oracle用户对配置文件的访问权限
[oracle@node1 admin]$ vi listener.ora
--添加参数INBOUND_CONNECT_TIMEOUT_LISTENER = 0
--添加参数DIAG_ADR_ENABLED_LISTENER = OFF
LISTENER=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER)))) # line added by Agent
LISTENER_SCAN1=(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=IPC)(KEY=LISTENER_SCAN1)))) # line added by Agent
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER_SCAN1=ON # line added by Agent
ENABLE_GLOBAL_DYNAMIC_ENDPOINT_LISTENER=ON # line added by Agent
INBOUND_CONNECT_TIMEOUT_LISTENER = 0
DIAG_ADR_ENABLED_LISTENER = OFF
~
~
[oracle@node1 admin]$ vi sqlnet.ora
--添加参数DIAG_ADR_ENABLED = OFF
--添加参数SQLNET.INBOUND_CONNECT_TIMEOUT =0
# sqlnet.ora.node1 Network Configuration File: /u01/11.2.0/grid/network/admin/sqlnet.ora.node1
# Generated by Oracle configuration tools.
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)
ADR_BASE = /u01/app/oracle
DIAG_ADR_ENABLED = OFF
SQLNET.INBOUND_CONNECT_TIMEOUT =0参考链接：https://blog.csdn.net/huangyanlong/article/details/46372849