Make sure that web2py starts showing that 'interbase' is available. The word 'password' is reserved in firebird, so change password fieldname in auth.
auth.settings.password_field='password2'
An example connect string...
db =
DAL('firebird://SYSDBA:[email protected]:3050//var/lib/firebird/2.1/data/testdata.fdb')
The folder can be anywhere. However, the permissions must be right. I
usually use file owner and group firebird:firebird.

