Ruby class that makes use of ruby 2.1's new Socket.getifaddrs

address.rb

require 'socket'
require 'netaddr'  # this is a gem

  class Address

    # Pull the ip address from the local machine
    def initialize
      @info = Socket.getifaddrs.find do |ifaddr|
        (ifaddr.flags & Socket::IFF_BROADCAST).nonzero? &&
          ifaddr.addr.afamily == Socket::AF_INET
      end 
    end 

    # Return ip address as string
    def ip_to_s
      @info.addr.ip_address
    end 

    # Return netmask as a string
    def mask_to_s
      @info.netmask.ip_address
    end 

    def start_address_to_s
      @info.addr.ip_address.split('.')[0..2].join('.') + ".0".to_s
    end 

    # Return Broadcast address as a string
    def broadcast_to_s
      @info.broadaddr.ip_address
    end 

    # Determine CIDR value based netmask
    def cidr_to_s
      NetAddr::CIDR.create('0.0.0.0/'+"#{mask_to_s}").netmask
    end 

  end