Hmm, did you look at the documentation (on the website I linked to)? PM isn't a place to come to if you want someone else to write you scripts. We're here to help, not do your work for you.

That being said, this will do what you say you want:

perl -MNet::Netmask -e'print "$_\n" for(Net::Netmask->new("10.1.1.0/20
+")->enumerate())'
[download]