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 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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