gistfile1.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-

require 'ethernet'

ETHER_NAME = 'lxcbr0'
socket = Ethernet.socket(ETHER_NAME, 0x0806)

OPERATION = 0x0002

dest_hw_address = Ethernet::Devices.mac(ETHER_NAME)

loop do
  message = socket.recv_from(4096)[0]
  hardware_type, protocol_type, hardware_len, protocol_len, operation, src_hw_address, src_protocol_address, _dest_hw_address, dest_protocol_address, _ = message.unpack('a2a2a1a1a2a6a4a6a4a*')

  if protocol_type == [0x0800].pack('n')
    if operation == [0x0001].pack('n')
        data = [hardware_type, protocol_type, hardware_len, protocol_len, OPERATION, dest_hw_address, dest_protocol_address, src_hw_address, src_protocol_address].pack('a2a2a1a1na6a4a6a4')
        socket.send_to(src_hw_address, data + 0x00.chr * 14)
    end
  end
end