gistfile1.rb

module Midterm
  class << self
    def ip_to_int(some_ip)
      parts = some_ip.split(".").map(&:to_i)
      (parts[0] << 24) + (parts[1] << 16) + (parts[2] << 8) + parts[3]
    end

    def int_to_ip(some_int)
      parts = Array.new(4)
      parts[0] = (some_int & (0xff << 24)) >> 24
      parts[1] = (some_int & (0xff << 16)) >> 16
      parts[2] = (some_int & (0xff << 8)) >> 8
      parts[3] = (some_int & (0xff << 0)) >> 0
      parts.map(&:to_s).join(".")
    end

    def mask(size)
      ("1" * size).ljust(32, "0").to_i(2)
    end
  end
end

module NumberHelpers
  def to_ip
    Midterm::int_to_ip(self)
  end
  
  def to_mask
    Midterm::mask(self)
  end
end

class Fixnum
    include NumberHelpers
end

class Bignum
    include NumberHelpers
end

class String
  def to_integer
    Midterm::ip_to_int(self)
  end
end


def net(ip, mask)
  (ip & mask).to_ip
end

def broadcast(ip, mask)
  (ip | ~mask).to_ip
end

Usage:

("192.168.13.5".to_integer & 28.to_mask).to_ip

Dir Red = IP & Mascara por default
Dir Subred = IP & Mask dada
Broadcast Red = OR con mascara default pero negada
Broadcast Subred = OR con máscara dado pero negada