Generate a random network block

get_private_network

#!/usr/bin/env ruby

@net172_octet_rejects = [nil, %w(16 20 24 31), %w(0 1)]
@net192_octet_rejects = [nil, nil, %w(0 1 2 3 4 5 6 7 8 9 10 168 254)]

def generate_net172(n=:C)
  begin
    octet_2 = (rand(16) + 16).to_s
  end while @net172_octet_rejects[1].include?(octet_2)

  return "172.#{octet_2}" if n == :B

  begin
  octet_3 = rand(256).to_s
  end while @net172_octet_rejects[2].include?(octet_3)

  "172.#{octet_2}.#{octet_3}"
end

def generate_net192(n=:C)
  begin
  octet_3 = rand(256).to_s
  end while @net192_octet_rejects[2].include?(octet_3)

  "192.168.#{octet_3}"
end

if ARGV[0] == "192"
  puts "Rejects are: #{@net192_octet_rejects.join(' ')}"
  puts "Class C: #{generate_net192 :C}"
else
  puts "Rejects are: #{@net172_octet_rejects.inspect}"
  puts "Class B: #{generate_net172 :B}"
  puts "Class C: #{generate_net172 :C}"
end