Fulvio Senore schrieb am 13.06.2012 um 22:17 (+0200):

> My purpose is very simple. The users can install the program on any
> number of computers connected to a Firebird server, and I want to
> limit the number of simultaneous connections.

Do you control the server? If you don't it'll be difficult to enforce
anything anyway. But if you do you might investigate whether it's
possible to configure this at the network level, like with iptables
on Linux, or whatnot on Windows. Take a look here, I didn't do further
checks so I don't know whether it's possible or not:

https://www.google.com/search?q=iptables+limit+number+of+connections

Michael