Enabling Line-Rate TLS SNI Inspection in P4 Programmable Data Planes
Ali AlSabeh, Ali Mazloum, Elie F. Kfoury, Jorge Crichigno, Hala Strohmier Berry · 2025
With the increasing adoption of the HyperText Transfer Protocol Secure (HTTPS), organizations face new challenges in monitoring traffic to defend against attacks and enforce security policies, such as filtering malicious websites. One widely used technique to monitor HTTPS is by scrutinizing the hostname in the Server Name Identification (SNI) extension during the Transport Layer Security (TLS) handshake. Parsing the SNI typically involves Deep Packet Inspection (DPI), often performed on general-purpose processors, which can create bottlenecks and significantly impact network throughput. In response, this paper introduces a novel framework for parsing and identifying SNI hostnames in the data plane at line-rate using P4. Evaluation results on recent publicly available datasets from various regions and platforms demonstrate that our framework can successfully parse 85%-99% of hostnames in P4. Furthermore, performance analysis reveals that the proposed data plane solution can inspect the hostname in approximately 1 microsecond (μ s), representing orders of magnitude improvement over solutions running on Central Processing Units (CPUs).