Switches are Scanners Too! A Fast and Scalable In-Network Scanner with Programmable Switches

Network scanning has been a standard measurement technique to understand the network's security situations, however, probing a large-scale scanning space with existing network scanners is both difficult and slow. To address this issue, we introduce IMap, a fast and scalable in-network scanner based on programmable switches. In designing IMap, we overcome key restrictions posed by computation models and memory resources of programmable switches, and devise numerous techniques and optimizations to turn a switch into a practical high-speed network scanner. We conduct preliminary experiments on the open-source prototype of IMap and evaluation results show that IMap can survey all addresses (i.e., 6 Class B Addresses) and all ports of our campus network in 8 minutes, nearly 4 times faster than state-of-the-art network scanners. As an ongoing work, we plan to continuously improve the design and implementation of IMap, and hope IMap can serve as a foundation for designing next-generation terabit network scanners.