@sorted = sort {
    ($$a[0] <=> $$b[0]) or
    ($$a[1] <=> $$b[1]) or
    ($$a[2] <=> $$b[2]) or
    ($$a[3] <=> $$b[3])
  } map {
    /(\d+)[.](\d+)[.](\d+)[.](\d+)/;
    [$1, $2, $3, $4]
  } @ip;
  my $previous = []; my @range = ();
  for $current (@sorted, [260, 0, 0, 0]) {
     if (greaterbyone($previous,$current) {
        $$previous[4] = $$current[3];
     } else {
        push @range, $previous;
        $previous = $current;
  }