> But both commands "ping localhost" and "ping 127.0.0.1" works with
> and without an Internet connection so what specific may be in the
> JDBC drivers ?

Driver opens socket connection using standard Java capabilities, so it
should not be a problem then. Try to write small Java application to open
connection using plain Java client sockets. If it wokrs, and JayBird still
does not, I have no idea :(

Also try following URL (you need jaybird.dll for this, that's type 2 JDBC
driver.)

jdbc:firebirdsql:native://localhost/e:/data/data.gdb

> Regarding Firebird-support: It's possible to connect to Firebird
> normally with isql even when no Internet connection, so what may I
> say them ? :-)

Do you try

CONNECT 'localhost:e:/data/data.gdb' USER 'sysdba' PASSWORD 'masterkey';

or just

CONNECT 'e:/data/data.gdb' USER 'sysdba' PASSWORD 'masterkey';

If latter, you connect to the server using IPC, network connection is not
used there.

Roman