Net::IPAddr is a collection of helpful functions used to convert
IP addresses to/from 32-bit integers, applying subnet masks to
IP addresses, validating IP address strings, and splitting a FQDN
into its host and domain parts.

No rocket science here, but I have found these functions to very,
very handy. For example, have you ever tried to sort a list of IP
addresses only to find out that they don't sort the way you expected?
Here is the solution! If you convert the IP addresses to 32-bit integer
addresses, they will sort in correct order.

WWW: http://search.cpan.org/dist/Net-IPAddress/