You are right, Adam,
I missed the fact that you where talking specifically about Windows.
But still, even on Linux, are "local connections" really local or is that
only a default redirection to localhost?
What I mean, can I avoid messing with inetd when I use
Classic Server with local connections only ?
How does firebird in that case detect the lock-manager running
and can talk to it?

I tried it out, using a naive approach:-):
I linked my application with fbclient lib instead of embedded.
On one box I had firebird (ClassicServer) installed with the original
script, i.e. all the root-stuff is done.
On that box I can run my application against firebird database no matter
if I write
"localhost:" in the database name or not.
Then I copied the installation to another box without running the
root-stuff.
There I get the error message "Unable to complete network request to
host "localhost".; Failed to establish a connection.; Connection refused;"
no matter if I write "localhost:" or not.
That makes me wonder if not "local connection" is just an implicit
network connection to localhost.
I have really read quite some documentation to try to get a picture of
that, but I didn't find a good explanation.

What must be done on a Linux box to enable firebird ClassicServer for
local connections?
What must be present, running ... ?
Can this be done without root access ?
Regards Thekla