Tnsping Utility Fails: ORA-12547, TNS-12537 - TCP.VALIDNODE_CHECKING is Enabled
(Doc ID 2252994.1)
Last updated on APRIL 12, 2017
Applies to:Oracle Net Services - Version 10.2.0.5 to 12.2 BETA1 [Release 10.2 to 12.2]
Information in this document applies to any platform.
Remote client connections and tnsping is failing to reach the listener. The listener is running and is working when tnsping and SQL*Plus are launched
locally or on the same server.
The tnsping trace shows this stack:
SQL*Plus remote connection might fail with:
TNS-12537 TNS: Connection closed
ORA-12547 TNS: Lost Contact
This is likely a new installation OR a new implementation of TCP.VALIDNODE_CHECKING.
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