Understanding the Challenges of Blocking Unnamed Network Traffic

Network traffic that is not preceded by any Domain Name System (DNS) resolutions is referred to as unnamed traffic. Any DNS-based security system is ineffective against malicious content distributed through this traffic. In this paper, we introduce a novel method for identifying unnamed traffic based on the correlation of flows and DNS responses extracted from raw network traces. We describe two challenges that affect the validity of our method, and how to handle them. By applying our method to a one-week trace of network traffic, we illustrate that unnamed traffic is ubiquitous in a university network across nearly all client systems, destination IP addresses, and destination services. We conclude by presenting several open problems that prevent us from blocking unnamed traffic for security reasons.