Net::netmask parses and understands ipv4 cidr blocks. it's built with an object-oriented interface. nearly all functions are methods that operate on a net::netmask object.

there are methods that provide the nearly all bits of information about a network block that you might want.

there are also functions to put a network block into a table and then later lookup network blocks by ip address in that table. there are functions to turn an ip address range into a list of cidr blocks. there are functions to turn a list of cidr blocks into a list of ip addresses.

there is a function for sorting by text ip address.