module for IPv4 subnet calculations

 Net::Subnets is a Perl module that provides a quick and simple method to
 perform miscellaneous operations with IP version 4 (IPv4) addresses. It can
 match a list of IP addresses against one or more CIDR (Classless Inter-Domain
 Routing) subnets. It also calculates ranges of IP addresses based on a subnet
 size, specified as a CIDR.