# File lib/aws/ec2/network_acl.rb, line 223
      def entry_options options

        unless [true,false].include?(options[:egress])
          msg = "expected :egress option to be set to true or false"
          raise ArgumentError, msg
        end

        entry_opts = {}
        entry_opts[:network_acl_id] = network_acl_id
        entry_opts[:rule_number] = options[:rule_number]
        entry_opts[:protocol] = options[:protocol].to_s.downcase
        entry_opts[:rule_action] = options[:action].to_s
        entry_opts[:egress] = options[:egress] if options.key?(:egress)
        entry_opts[:cidr_block] = options[:cidr_block]

        if options[:icmp_code] or options[:icmp_type]
          entry_opts[:icmp_type_code] = {}
          entry_opts[:icmp_type_code][:type] = options[:icmp_type]
          entry_opts[:icmp_type_code][:code] = options[:icmp_code]
        end

        if options[:port_range]
          entry_opts[:port_range] = {}
          entry_opts[:port_range][:from] = options[:port_range].first
          entry_opts[:port_range][:to] = options[:port_range].last
        end

        entry_opts

      end