# File firewall/lib/symbiosis/firewall/logtail.rb, line 32
      def identifier
        return @identifier unless @identifier.nil?

        line = nil
        File.open(self.filename) do |fh|
          line = fh.gets
        end

        if line.is_a?(String)
          @identifier = Digest::MD5.new.hexdigest(line)
        else
          @identifier = nil
        end

        @identifier
      end