Oracle Error Message
ORA-03136: inbound connection timed out
Reason for the Error
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
Solution
1) Check SQL*NET and RDBMS log for trace of suspicious connections. 2) Configure SQL*NET with a proper inbound connect timeout value if necessary.