Tuesday, August 19, 2014

WARNING: inbound connection timed out (ORA-3136)

Warning message inbound connection timed out (ORA-3136) can be seen in the alert log file if a client was failed to authenticate itself within a specified period of time, since connection was initiated first time. sqlne.ora parameter called "SQLNET.INBOUND_CONNECT_TIMEOUT" is used to specify a value in number of seconds, database would
wait for connection to be established before logging this warning message in alert log file.

This parameter has no default value in 9i, but has a default value of 60 seconds in later versions. This parameter serves for the security and alerts (by issuing warning) if someone tries to connect with the database and initial connection effort was turned down (because of wrong password) and session has not tried to reconnect during this specified period of time. With the warning message in alert log file, the IP address of the client is also logged in SQLNET.LOG file.

In the following you can see how this WARNING message can be deliberately produced.


In my database, I have not set any value for SQLNET.INBOUND_CONNECT_TIMEOUT in SQLNET.ORA and hence it has default value of 60 seconds. In the following image, upper screen shows my initial attempt to connect with the database with wrong password, and in lower screen; exactly after 60 seconds of initial session attempt, this warning message is logged in alert log file.

If you don't want to see this kind of warnings in alert log file, you can set the value of this parameter to 0 which would mean that database would indefinitely wait for the session to be authenticated without logging any error message


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