It wasn’t long before I needed to expand upon banning a few IP’s. I needed to be able to ban whole networks so here’s the Q&D solution:-
First create a text file called ipsec.txt and enter some IP’s you wish to ban, to ban a network just leave off the end of the IP class [...]

This demonstrates how to ban a single IP address, later, I’ll show how to ban whole networks but chances are you will be able to work that out for yourself anyway after reading this anyway.
If global.asa does not exist then create it and add the following:

sub session_onstart
 
ip = request.servervariables("Remote_Addr")
 
select case ip
[...]