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Linux: Remote SQL*Plus and Tnspings with Timeouts While Loopback is Successful (Doc ID 340661.1)

Last updated on JANUARY 08, 2020

Applies to:

Oracle Net Services - Version to [Release 8.1.7 to 12.1]
Linux x86
Linux x86-64
Checked for relevance on 5-FEB-2010.


The listener is running and appears to be functioning properly when using TCP loopback connections on the server.   However, remote clients attempting to contact the server via TCP using either SQL*Plus or tnsping are failing with an ORA-12560.   Remote client connections may also hang or throw a timeout error.  TNS-12535. 

A client trace file might reveal the following:

Consider this document for any of the following errors or conditions using SQL*Plus or Tnsping and when Linux is the platform where the database resides:

ORA-12560 TNS:  Protocol adapter error

ORA-12535  TNS:  Operation timed out
TNS-12535 TNS: Operation timed out

If remote clients using SQL*Plus hang indefinitely, this may be the problem.


The database server is either Linux x86 or x86-64 and this is likely a new installation.


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