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.

Symptoms

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

Changes

 This is likely a new installation OR a new implementation of TCP.VALIDNODE_CHECKING.

Cause

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