well, I can't wait - probably the best place to insert lines is in connect
method:

try {
db.socket = new Socket(dbai.getServer(), dbai.getPort());
db.socket.setReceiveBufferSize(16 * 1024);
db.socket.setSendBufferSize(16 * 1024);
if (log != null) log.debug("Got socket");
} catch (UnknownHostException ex2) {
String message = "Cannot resolve host " + dbai.getServer();
if (log != null) log.error(message, ex2);
throw new GDSException(isc_arg_gds, isc_network_error,
dbai.getServer());
}

but still no way - the code throws exception:

java -classpath
.:myfirebirdsql.jar:mini-concurrent.jar:mini-j2ee.jar:jaas.jar:log4j-core.ja
r test linux fb > linux_fb_a.log
Exception in thread "main" java.lang.VerifyError: (class:
org/firebirdsql/jgds/GDS_Impl, method: releaseObject signature:
(Lorg/firebirdsql/jgds/isc_db_handle_impl;II)V) Incompatible object argument
for function call
at org.firebirdsql.gds.GDSFactory.cloneClumplet(GDSFactory.java:60)
at
org.firebirdsql.jca.FBConnectionRequestInfo.<init>(FBConnectionRequestInfo.j
ava:55)
at
org.firebirdsql.jdbc.FBConnectionHelper.getCri(FBConnectionHelper.java:153)
at org.firebirdsql.jdbc.FBDriver.connect(FBDriver.java:223)
at java.sql.DriverManager.getConnection(DriverManager.java:512)
at java.sql.DriverManager.getConnection(DriverManager.java:171)
at test.main(test.java:45)

Roman, can you make changes and check driver?
Thanks,
Sergei Volin.