libnet-netmask-perl 1.9104-1 (amd64 binary) in ubuntu hirsute

 Net::Netmask parses and understands IPv4 and IPv6 CIDR blocks. It's built
 with an object-oriented interface, with functions being methods that operate
 on a Net::Netmask object.
 .
 These methods provide nearly all types of information about a network block
 that you might want.
 .
 There are also functions to insert a network block into a table and then
 later lookup network blocks by IP address using that table. There are
 functions to turn a 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.
 .
 All functions understand both IPv4 and IPv6. Matches, finds, etc, will always
 return false when an IPv4 address is matched against an IPv6 address.