Returns a list of 'good' port ranges.
    Such ranges are large and don't contain ephemeral or well-known ports.
    Ranges borders are also excluded.

def good_port_ranges(ports=None, min_range_len=20, border=3):
    """
    Returns a list of 'good' port ranges.
    Such ranges are large and don't contain ephemeral or well-known ports.
    Ranges borders are also excluded.
    """
    min_range_len += border*2
    if ports is None:
        ports = available_ports()
    ranges = utils.to_ranges(list(ports))
    lenghts = sorted([(r[1]-r[0], r) for r in ranges], reverse=True)
    long_ranges = [l[1] for l in lenghts if l[0] >= min_range_len]
    without_borders = [(low+border, high-border) for low, high in long_ranges]
    return without_borders