在進行Oracle數據庫巡檢中常常在日志中發現這樣的錯誤日志，但是卻通常不會影響客戶使用。

整體報錯如下：

*********************************************************************** 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

通過查看官方文檔說明：

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.

這個意思是：
TNS連接超時
原因是客戶端無法在指定的時間內建立連接并完成身份驗證SQLNET.INBOUND CONNECT超時中的參數sqlnet.ora文件。此錯誤可能是 由于網絡或系統延遲造成的，也可能表示惡意客戶端正試圖對數據庫服務器造成拒絕服務攻擊。
從最終的結果數據庫還可以正常使用來看，這是出現了延遲造成的。根據網上的相關錯誤處理辦法。由于在Automatic Diagnostic Repository中的 Oracle Net diagnostic是開啟狀態，從而對連接延遲錯誤進行獲取并且將其寫入告警日志。解決的辦法就是將自動診斷關于網絡診斷的配置關閉即可。
其實整個報錯這個問題并沒有什么影響，如果沒有特殊需求可以不關閉。
參考網絡上解決方式：

【解決方式】

[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
--確認oracle用戶對配置文件的訪問權限
[oracle@node1 admin]$ vi listener.ora
--添加參數INBOUND_CONNECT_TIMEOUT_LISTENER = 0
--添加參數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
--添加參數DIAG_ADR_ENABLED = OFF
--添加參數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

參考鏈接： https://blog.csdn.net/huangyanlong/article/details/46372849