This is the Net::IP module, designed to allow easy manipulation of IPv4 and IPv6 addresses. You need to have Math::BigInt installed on your system. You install the library by running these commands: perl Makefile.PL make make test make install There is also a small application which uses the IP.pm module: ipcount.pl. Basically, it's an IP address mini-calculator, it can calculate the number of IP addresses in a prefix or all the prefixes contained in a given range. All bug reports and suggestions for improvemenets should be sent to Manuel Valente . Many thanks to Ulrich Wisser for the version 1.26. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.