I already block some simple ip lighttpd but I want to block a whole network. I've problem to understand what is this network address for example 10.0.0.0/8 and/or 172.16.2.0/24 network? What is this /8 or /24 means? I use $HTTP["remoteip"] to add my ip I want to deny the access.
The numbers after the slashes are subnet prefixes in CIDR notation (they're just another way to express subnet masks). Subnets and CIDR are a pretty fundamental concept in IP networking and you won't avoid learning how they work.
It even works with numbers that aren't multiples of eight:
and you'll get the best subnets that describe the range (there will likely be more than one, and they all have to be specified to describe the range).
If you just want to specify one address, you either leave out the