A very simple utility to work with CIDR ranges; it can list all IP addresses in a range or check if an address is part of a range.

To list all addresses in a range:

netmask 192.168.0.0/24

To check if an address is part of a range:

netmask 192.168.0.0/24 192.168.0.1

The exit code will be 0 if the address is part of the range and 1 if it isn't.