Thanks for your suggestions.

I am actually searching for another way. This database is part of an application that is deployed at our customers.

In the new firebird release it is possible to choose security authentication via external .fbd file or programmed into the database itself.

We want to use the authentication in our own database and prevent any use of .fdb files for access. Now if a customer has our database, he simply can set security3.fdb and gain access to the DB.

Is there any way to prevent this and only use our authentication ?

regards Roland