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ORA-03136: inbound connection timed out  tips

Oracle Error Tips by Burleson

Oracle docs note this about ORA-03136:

ORA-03136: inbound connection timed out
Cause: Inbound connection was timed out by the server because user authentication was not completed within the given time specified by SQLNET.INBOUND_CONNECT_TIMEOUT or its default value

   1) Check SQL*NET and RDBMS log for trace of suspicious connections.
   2) Configure SQL*NET with a proper inbound connect timeout value if

Troubleshooting ORA-03136  can be pretty tricky, but Oracle MOSC offers information on ORA-03136 in Oracle Net Services, version 10.2.  There can be three main reasons for the ORA-03136 error

1) The server gets a connection request from a malicious client which is not allowed to connect to Oracle, in which case the ORA-03136 error is the correct behavior. You can get the client address for which the error was thrown via sqlnet log file.

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

3) The server is heavily loaded or more of RAM usage due to which it cannot finish the client logon within the timeout specified.

ORA-03136 means that an authentication was not able to be completed, and can appear without a timeout error with in the sqlnet.log file.  It is important to that from 10.2 on, the parameter has a default of 60 seconds, and when the client attempts to authenticate it will often throw ORA-03136.

To figure out which issue is causing your ORA-03136, try these checks, especially considering that in many conditions, the default setting offers enough resources for authenticating client connections:

1. Check whether local connection on the database server is successful & 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.

Also, on Oracle Forums, there is information regarding ORA-03136 and issues with INBOUND_CONNECTION_TIMEOUT.  If the listener does not receive the command correctly, it will shutdown and throw errors such as ORA-03136. 

For more information regarding INBOUND_CONNECTION_TIMEOUT to help resolve ORA-03136, try this article.

 And you may want to also review these notes on ORA-12170




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