TCP behavior with OJDBC

User_FH29L

Hello,

I hope this is the right place to ask, do not hesitate to correct me if needed.

I have an issue with the TCP handshake of the JDBC version 19.12.0.0.0. The connection to the Oracle DB is not established because during the initial handshake, the driver sends a packet with the TCP flags "PSH, ACK, URG" and this very packet is dropped by the firewall sitting between the client and the server because it is considered as "malformed".

I have tested with and the OJDBC version 12.2.0.1.0 and we don't have any issue because there's no special TCP flags used.

My question is : is the use of the TCP flags "PSH, ACK, URG" an expected behavior from the OJDBC driver ? Why did it change between those two OJDBC versions ?

Thanks in advance for your help.

Best regards

MichaelFromOracle-Oracle

Hi there,

I believe this is JDBC testing if the network connection will support out-of-band (OOB) TCP urgent bytes. The driver can send an OOB byte to cancel a long running database call (this typically happens when a statement timeout expires).

If this is causing an issue, then you can try setting a connection property that disables the use of OOB entirely:

oracle.net.disableOob=true

https://docs.oracle.com/en/database/oracle/oracle-database/21/jajdb/oracle/jdbc/OracleConnection.html#CONNECTION_PROPERTY_THIN_NET_DISABLE_OUT_OF_BAND_BREAK

Cancelling database calls with OOB is a bit faster than the alternative of cancelling with an in-band message. That is, you'll see the ORA-01013 error come back sooner than you would otherwise. If you really want fast cancellation, then allowing OOB bytes to pass through the firewall would be another option.

Thanks,

Michael

MichaelFromOracle-Oracle

Hi there,

I believe this is JDBC testing if the network connection will support out-of-band (OOB) TCP urgent bytes. The driver can send an OOB byte to cancel a long running database call (this typically happens when a statement timeout expires).

If this is causing an issue, then you can try setting a connection property that disables the use of OOB entirely:

oracle.net.disableOob=true

https://docs.oracle.com/en/database/oracle/oracle-database/21/jajdb/oracle/jdbc/OracleConnection.html#CONNECTION_PROPERTY_THIN_NET_DISABLE_OUT_OF_BAND_BREAK

Cancelling database calls with OOB is a bit faster than the alternative of cancelling with an in-band message. That is, you'll see the ORA-01013 error come back sooner than you would otherwise. If you really want fast cancellation, then allowing OOB bytes to pass through the firewall would be another option.

Thanks,

Michael

User_FH29L

Great ! You were right and changing the property solved my issue.

Thanks a lot Michael.