sub get_boundaries {
    my ($ip, $bits) = split /\//, $_[0];
    my $b_ip        = pack "C4", split /\./, $ip;
    my $b_mask      = pack "B32", 1 x $bits;
    my $b_net       = $b_ip  &  $b_mask;
    my $b_bcast     = $b_ip | ~ $b_mask;
    unpack("N", $b_net), unpack("N",  $b_bcast);
}