> [snip]
> > So it seems to be a firebird issue... is there any way to
> > track firebird's actions, like debug output or so?
> > I think I'll strace a bit.. I'll check in later if I have success :)
>
> Ok... strace didn't help me much, either.
> I can't see what's exactly going wrong...
> I've attached 2 strace log-files. One where the
> client connects successfully (my box) and
> one where another client connects, which fails.
> Perhaps you have better eyes and better
> knowledge to see the error. :)
>
> I hope the mailinglist allows attachments...
>
> cu,
> Daniel
>

I think you are making something far bigger out of this than it probably is.
Please check that the client libraries on your clients match that of the
server. The "connection refused" message is notoriously associated with
outdated client libs. i.e. an old gds32.dll from interbase or previous FB
install on those client machines.
Alan