#!/usr/bin/perl
# file cidr
$m=pack B32,pop=~'/'x$';
printf"$` network %vd broadcast %vd netmask %vd\n",($z=eval$`)&$m,$z|~$m,$m;
__END__
Example:
cidr 209.197.123.153/27
209.197.123.153 network 209.197.123.128 broadcast 209.197.123.159 netmask 255.255.255.224