My setup is as follows:
- instance1 responds to ip1, has "DatabaseAccess = None" in
firebird.conf and "test = /test.fdb" in aliases.conf
- instance2 responds to ip2 and has "DatabaseAccess = Full" in
firebird.conf and no aliases.conf file.

After I start the two instances, they *are* both running, the logs
show no error, but what happens when I connect is very weird: The
servers respond on both ip1 and ip2, but I can only attach the
database allowed by the server I started first. It's like the second
instance obeys the DatabaseAccess option of the first instance.

So anyway, I'm out of ideas. Did anybody managed to run two instances
of fbserver on a linux machine in any way?