> With the "pure java" class 4 driver --- no way as it seems. I always
> got the same error message during my tests - could not complete
> network request to host "..."

Try telnet <hostname> 3050. If you cannot get connection on that port, you
have to check if your inetd is started and /etc/inetd.conf contains correct
entries. Also you have to check whether that is not xinetd that should be
started.

> Does anyone have an idea why this doesn't work?
> Is the class 2 driver better or faster anyway?

class 2 driver is faster if you connect to localhost without specifying the
host name. Then on Windows it uses IPC instead of local loopback. I cannot
tell you whether IPC is used on Linux, most likely it is accesses the
database file direct using gds_lock_manager to coordinate its work with
other instances. More information you get in Firebird-support. But if you
access remote host, type 2 is ~10% slower compared to type 4.

Roman