Okay, the firewall script is now running and it is nice and stable.
It works with a second SQL database so the forum database is not used.
It blocks every IP number, that makes too many hits to the forum
in each xx minutes intervals.
If an IP address (user) is caught making more hits, then
his IP address is automatically blocked and he gets a 403 error page,
where it tells him, that he is blocked due to that he made too much traffic.
The ban can be lifted later or not, depending on rules..
P.S. Now I have enabled also again the RSS-Feeds, cause these
users can´t abuse anymore the traffic !