Problems with desupported clients after server migration to 11.2.0.2
We are planning to migrate our database from 10.2.0.4 on Windows Server 2003 (32-bit) to 11.2.0.2 on Windows Server 2008 R2 (64-bit). Therefore we installed a test server and did a test migration of our development database instance. The migration itself worked quite well. Accessing the new test server using supported clients also succeded.
The problem is that we still have Windows clients in our company that have a (desupported) Oracle 7.3 Client and ODBC Driver (Oracle73 Ver 2.5, SQO32_73.DLL) installed. Each connection attempt by such a client (if they know the server's IP address and instance name) results in one server CPU core going to 100% CPU Usage. The clients gets an "ORA-03113: end-of-file on communication channel." error. The core CPU usage stays at 100% until the database is shut down.
Setting "SQLNET.ALLOWED_LOGON_VERSION = 10" in SQLNET.ORA does not solve the problem. It seems that the listener allows the connection and then something goes wrong before the connection can be blocked by SQL*NET.
Any ideas how to detect and prevent connection attempts by Oracle 7.3 clients at a lower level? I already did a lot of research on the net without finding a solution. Thanks in advance!