use 5.022;
use warnings;

my @netmasks;
my $value = 0xfffffffe;

for my $maskLen ( reverse 0 .. 31 )
{
    unshift @netmasks, pack q{N}, $value;
    $value = do {
       no warnings qw{ portable };
       ( $value <<= 1 ) % 0x100000000;
       };
}

say for map { unpack q{B32}, $_ } @netmasks;