in_addr

# File lib/ipaddr.rb, line 445
  def in_addr(addr)
    if addr =~ /^\d+\.\d+\.\d+\.\d+$/
      n = 0
      addr.split('.').each { |i|
        n <<= 8
        n += i.to_i
      }
      return n
    end
    return nil
  end