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Denodo ODBC connection with Kerberos becomes invalid after an attempt to execute bad SQL query

Hello Denodo Team, my customer uses my ad-hoc query tool to connect to Denodo Virtual Data Port using ODBC driver with Kerberos authentication. All works fine, until the user tries to execute SQL query with error in it. The query fails as expected and Denodo VDP returns correct error message, but the connection becomes invalid, and now sending even valid queries always return error: ``` [ODBC]ERROR: authentication error: No valid Kerberos authentication for user: Failure unspecified at GSS-API level (Mechanism level: Request is a replay (34)) java.sql.SQLException: authentication error: No valid Kerberos authentication for user: Failure unspecified at GSS-API level (Mechanism level: Request is a replay (34)); Error while executing the query ``` Should I reconnect after every error or it is a driver or Kerberos configuration issue?
user
18-01-2022 08:32:08 -0500
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1 Answer

Hi, Denodo Platform deals with cursors over ODBC connections. In this kind of situation, Denodo needs to create several connections against a Virtual DataPort server using the same user credential. But in general if the user uses Kerberos Authentication, the same ticket is being validated several times. However, JVM allows a Kerberos ticket to be validated once by default. As a result, the ODBC connection fails with the error “authentication error: No valid Kerberos Authentication for user: Failure unspecified at GSS-API level (Mechanism Level : Request is a replay 34)”. In order to resolve this issue, perform the below steps in JVM configuration to validate the same ticket more than once: * Add the following to the JAVA_OPTS property in the VDBConfiguration.properties which is located under the directory “<Denodo_Home>/conf/vdp”. >**-Dsun.security.krb5.rcache=none** * Restart the server for the changes to take effect. Besides, you can enable the “**Server side prepare**” option in the ODBC configuration settings in the Driver connection settings of the DSN setting. For more information, you could refer to the [DSN configuration for ODBC connections to VDP](https://community.denodo.com/kb/en/view/document/DSN%20configuration%20for%20ODBC%20connections%20to%20VDP) in the Knowledge Base article. Hope this helps!
Denodo Team
19-01-2022 06:07:22 -0500
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