Thanks for the reply Boofo.
That may fix *some* of my problem.
This flooder that hit my site had 1300 guest sessions, all trying to register or use the 'lost password' form. All from the same IP address.
This is a small private site. We have 65 members and will probably never have more than 100. There is never more than 20 members on the site at any given time.
What I need is something that will not allow 1300 connections from the same IP address, no matter what page it is viewing.

That is just rediculous.
Or something that will display an error message at the login screen if there are more than 'X' number of guests online.
A combination of both is a plus