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Oracle10.2.0.3 ORA-3136 wrong solution, I believe that many inexperienced people do not know what to do, so this paper summarizes the causes of the problem and solutions, through this article I hope you can solve this problem.

1. Problem phenomenon

The alert log file reports the following error

WARNING: inbound connection timed out (ORA-3136)

Mon Oct 20 14:33:52 2008

WARNING: inbound connection timed out (ORA-3136)

Mon Oct 20 14:34:46 2008

WARNING: inbound connection timed out (ORA-3136)

The following error is logged in sqlnet.log:

Fatal NI connect error 12170.

VERSION INFORMATION:

TNS for Linux: Version 10.2.0.3.0-Production

Oracle Bequeath NT Protocol Adapter for Linux: Version 10.2.0.3.0-Production

TCP/IP NT Protocol Adapter for Linux: Version 10.2.0.3.0-Production

Time: 20-OCT-2008 14:34:46

Tracing not turned on.

Tns error struct:

Ns main err code: 12535

TNS-12535: TNS:operation timed out

Ns secondary err code: 12606

Nt main err code: 0

Nt secondary err code: 0

Nt OS err code: 0

Client address: (ADDRESS= (PROTOCOL=tcp) (HOST=192.168.123.103) (PORT=3124))

The following solutions are given on 2.Metalink

1) set INBOUND_CONNECT_TIMEOUT_=0 in listener.ora

2) set SQLNET.INBOUND_CONNECT_TIMEOUT = 0 in sqlnet.ora of server.

3) stop and start both listener and database.

4) Now try to connect to DB and observe the behaviour

If you do not restart and just reload, you can also modify it successfully.

Verify whether the modification is successful by the following way

LSNRCTL > show inbound_connect_timeout

The method of modifying inbound_connect_timeout parameters of listener

Method 1:

$lsnrctl

LSNRCTL for IBM/AIX RISC System/6000: Version 10.2.0.3.0-Production on 29-OCT-2007 10:00:57

Copyright (c) 1991, 2006, Oracle. All rights reserved.

Welcome to LSNRCTL, type "help" for information.

LSNRCTL > help

The following operations are available

An asterisk (*) denotes a modifier or extended command:

Start stop status

Services version reload

Save_config trace spawn

Change_password quit exit

Set* show*

LSNRCTL > show

The following operations are available after show

An asterisk (*) denotes a modifier or extended command:

Rawmode displaymode

Rules trc_file

Trc_directory trc_level

Log_file log_directory

Log_status current_listener

Inbound_connect_timeout startup_waittime

Snmp_visible save_config_on_stop

Dynamic_registration

LSNRCTL > show inbound_connect_timeout

Connecting to (ADDRESS= (PROTOCOL=tcp) (HOST=) (PORT=1521))

LISTENER parameter "inbound_connect_timeout" set to 60

The command completed successfully

LSNRCTL > set inbound_connect_timeout 0

Connecting to (ADDRESS= (PROTOCOL=tcp) (HOST=) (PORT=1521))

LISTENER parameter "inbound_connect_timeout" set to 0

The command completed successfully

LSNRCTL > show inbound_connect_timeout

Connecting to (ADDRESS= (PROTOCOL=tcp) (HOST=) (PORT=1521))

LISTENER parameter "inbound_connect_timeout" set to 0

The command completed successfully

LSNRCTL > set save_config_on_stop on # means that the modified parameter will take effect permanently, otherwise it will only take effect temporarily, and the next time you restart the listening, it will return to the original value.

LSNRCTL > exit

Method 2:

Modify the listener.ora file by adding: INBOUND_CONNECT_TIMEOUT_LISTENER_NAME=0

Subject: Troubleshooting ORA-3136 WARNING Inbound Connection Timed Out

Doc ID: Note:465043.1 Type: TROUBLESHOOTING

Last Revision Date: 30-JUN-2008 Status: PUBLISHED

In this Document

Purpose

Last Review Date

Instructions for the Reader

Troubleshooting Details

Applies to:

Oracle Net Services-Version: 10.2.0.1.0

Information in this document applies to any platform.

Purpose

Troubleshooting guide for "ORA-3136 WARNING inbound connection timed out" seen in the alert log.

Last Review Date

July 1, 2008

Instructions for the Reader

A Troubleshooting Guide is provided to assist in debugging a specific issue. When possible, diagnostic tools are included in the document to assist in troubleshooting.

Troubleshooting Details

The "WARNING: inbound connection timed out (ORA-3136)" in the alert log indicates that the client was not able to complete it's authentication within the period of time specified by parameter SQLNET.INBOUND_CONNECT_TIMEOUT.

You may also witness ORA-12170 without timeout error on the database server sqlnet.log file.

This entry would also have the clinet address which failed to get authenticated. Some applications or JDBC thin driver applications may not have these details.

From 10.2 onwards the default value of parameter SQLNET.INBOUND_CONNECT_TIMEOUT is 60 seconds, hence if the client is not able authenticate within 60 secs, the warning would appear in the alert log and the client connection will be terminated.

Note: This timeout restriction was introduced to combat Denial of Service (DoS) attack whereby malicious clients attempt to flood database servers with connect requests that consumes resources.

There can be three main reasons for this error-

Server gets a connection request from a malicious client which is not supposed to connect to the database, in which case the error thrown is the correct behavior. You can get the client address for which the error was thrown via sqlnet log file.

The server receives a valid client connection request but the client takes a long time to authenticate more than the default 60 seconds.

The DB server is heavily loaded due to which it cannot finish the client logon within the timeout specified.

To understand what is causing this issue, following checks can be done

The default value of 60 seconds is good enough in most conditions for the database server to authenticate a client connection. If its taking longer period, then its worth checking all the below points before going for the workadound:

Check whether local connection on the database server is sucessful & quick.

2. If local connections are quick, then check for underlying network delay with the help of your network administrator.

3. Check whether your Database performance has degraded by anyway.

4. Check alert log for any critical errors for eg, ORA-600 or ORA-7445 and get them resolved first.

These critical errors might have triggered the slowness of the database server.

As a workaround to avoid only this warning messages, you can set the parameters SQLNET.INBOUND_CONNECT_TIMEOUT

And

INBOUND_CONNECT_TIMEOUT_

To the value more than 60.

For e.g 120. So that the client will have more time to provide the authentication information to the database. You may have to further tune these parameter values according to your setup.

To set these parameter-

1. In server side sqlnet.ora file add

SQLNET.INBOUND_CONNECT_TIMEOUT

For e.g

SQLNET.INBOUND_CONNECT_TIMEOUT = 120

2. In listener.ora file-

INBOUND_CONNECT_TIMEOUT_ = 110,

For e.g if the listener name is LISTENER then-

INBOUND_CONNECT_TIMEOUT_LISTENER = 110,

From Oracle version 10.2.0.3 onwards the default value of INBOUND_CONNECT_TIMEOUT_ is 60 seconds. For previous releases it is zero by default.

How to check whether inbound timout is active for the listener and database server

For eg. INBOUND_CONNECT_TIMEOUT_ = 4

You can check whether the parameter is active or not by simply doing telnet to the listener port.

$telnet

For eg.

$telnet 192.168.12.13 1521

The telnet session should disconnect after 4 seconds which indicates that the inbound connection timeout for the listener is active.

To check whether database server sqlnet.inbound_connect_timeout is active:

Eg.

Sqlnet.inbound_connect_timeout = 5

A. For Dedicated server setup, enable the support level sqlnet server tracing will show the timeout value as below:

Niotns: Enabling CTO, value=5000 (milliseconds)

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