Identifying Services and Devices Efficiently with a TCP Stateless Scanning Model

Fast large-scale network scanning is an important way to understand internet service configurations and security in real time, among which stateless scan technology is representative. Existing stateless scanners can perform single-packet scans for internet-wide network measurements but are limited to host discovery or port scanning. To obtain further information over TCP, slower stateful scanners must be used in conjunction, which spend more time and memory because of connection state maintenance. Through the simplification of the TCP finite state machine (FSM), this paper proposes a novel stateless scanning model, which can establish TCP connections and obtain further responses in a completely stateless manner. Based on this model, we implement ZBanner, an improved modular stateless scanner that utilizes user-defined probes for identifying services and versions, fingerprinting TLS servers, etc. We present the unique design of ZBanner and experimentally characterize its feasibility and performance. Experiments show that ZBanner performs better than current state-of-the-art solutions in terms of scan rate and memory usage. ZBanner achieves a scan rate that is at least three times faster than current tools for generic ports and over 90 times faster for open ports while keeping a minimum and stable memory usage.