New Connections Intermittently Rejected with TNS-12525

(Doc ID 566886.1)

Last updated on AUGUST 24, 2017

Applies to:

Oracle Net Services - Version 10.2.0.1 to 11.2.0.4 [Release 10.2 to 11.2]
Oracle Net Services - Version 12.1.0.2 to 12.1.0.2 [Release 12.1]
Information in this document applies to any platform.
***Checked for relevance on 20-DEC-2013***



Symptoms

At regular intervals (every three hours), you see new connections rejected with TNS-12525 "listener has not received client's request in time allowed".

The listener log shows the following error stack :

10-APR-2008 17:39:15 * <unknown connect data> * (ADDRESS=(PROTOCOL=tcp)(HOST=XX.XXX.XXXX)(PORT=4184)) * establish * <unknown sid> * 12525
  TNS-12525: TNS:listener has not received client's request in time allowed
    TNS-12535: TNS:operation timed out
      TNS-12606: TNS: Application timeout occurred


At the same time the firewall log reports :

"TCP packet out of state: First packet isn't SYN; tcp_flags: PUSH-ACK"


Wireshark (Ethereal) traces show the TCP 3-way handshake never completes for those connections.

Changes

Value of idle timer was recently changed at firewall level.

Cause

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