NetCloak: Dynamic Topology Expansion for Secure and Scalable Configuration Sharing

As modern networks continue to grow in both scale and complexity, sharing real-world device configurations poses significant privacy risks, especially when adversaries can infer organizational size or resource distribution from topology data. We present NetCloak, a configuration anonymization framework that adaptively injects synthetic routers and hosts into the network graph to obfuscate true scale, while preserving end-to-end forwarding behavior. NetCloak core techniques include: (1) a graph-embedding expansion algorithm that integrates the original topology into a larger reference graph, ensuring added nodes blend seamlessly with real ones; (2) a k-degree mapping anonymity scheme that selectively adds minimal links to guarantee each original node degree is indistinguishable among at least k peers; (3) a mimicry-driven configuration generator that derives command templates from existing devices, preserving command ordering, naming conventions, and routing policies; and (4) a layered repair process combining SMT-based intra-AS route synthesis with iterative inter-AS filter insertion to restore protocol-correct routing under OSPF and BGP. Extensive experiments on real and emulated campus and data-center topologies demonstrate that NetCloak effectively conceals network size, improving topological rationality by over 70% and configuration fidelity by nearly 30% compared to baseline methods, while reducing route-repair overhead by more than 50% under randomized link costs. NetCloak thus enables safe, privacy-preserving configuration sharing at scale.