'Net::CIDR::Set' represents sets of IP addresses and allows standard set
operations (union, intersection, membership test etc) to be performed on
them.

In spite of the name it can work with sets consisting of arbitrary ranges
of IP addresses - not just CIDR blocks.

Both IPv4 and IPv6 addresses are handled - but they may not be mixed in the
same set. You may explicitly set the personality of a set:

my $ip4set = Net::CIDR::Set->new({ type => 'ipv4 }, '10.0.0.0/8');

Normally this isn't necessary - the set will guess its personality from the
first data that is added to it.