Generally, user = SYSDBA with password = masterkey is worth a try.

Set
-who lived in Søren Jaabæks gate until recently...

--- In firebird-support@yahoogroups.com, John Jaabæk wrote:
> Looking for the original password for Firebird 1.5 on Linux..
> --
>
> John H. Jaabæk
> tlf. +47 915 24 599
> Uavhengig Velværekonsulent for Nikken
> http://www.nikken.com
> http://www.nikkenuk.com