Wang, Anduo
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Publication Declarative Network Verification(2008-12-23) Wang, Anduo; Basu, Prithwish; Loo, Boon Thau; Sokolsky, OlegIn this paper, we present our initial design and implementation of a declarative network verifier (DNV). DNV utilizes theorem proving, a well established verification technique where logic-based axioms that automatically capture network semantics are generated, and a user-driven proof process is used to establish network correctness properties. DNV takes as input declarative networking specifications written in the Network Datalog (NDlog) query language, and maps that automatically into logical axioms that can be directly used in existing theorem provers to validate protocol correctness. DNV is a significant improvement compared to existing use case of theorem proving which typically require several man-months to construct the system specifications. Moreover, NDlog, a high-level specification, whose semantics are precisely compiled into DNV without loss, can be directly executed as implementations, hence bridging specifications, verification, and implementation. To validate the use of DNV, we present case studies using DNV in conjunction with the PVS theorem prover to verify routing protocols, including eventual properties of protocols in dynamic settings.Publication Formally Verifiable Networking(2009-10-01) Wang, Anduo; Jia, Limin; Liu, Changbin; Loo, Boon Thau; Sokolsky, Oleg; Basu, PrithwishThis paper proposes Formally Verifiable Networking (FVN), a novel approach towards unifying the design, specification, implementation, and verification of networking protocols within a logic-based framework. In FVN, formal logical statements are used to specify the behavior and the properties of the protocol. FVN uses declarative networking as an intermediary layer between high-level logical specifications of the network model and low-level implementations. A theorem prover is used to statically verify the properties of declarative network protocols. Moreover, a property preserving translation exists for generating declarative networking implementations from verified formal specifications. We further demonstrate the possibility of designing and specifying well-behaved network protocols with correctness guarantees in FVN using meta-models in a systematic and compositional way.Publication A Theorem Proving Approach Towards Declarative Networking(2009-08-01) Wang, Anduo; Loo, Boon Thau; Liu, Changbin; Sokolsky, Oleg; Basu, PrithwishWe present the DRIVER system for designing, analyzing and implementing network protocols. DRIVER leverages declarative networking, a recent innovation that enables network protocols to be concisely specified and implemented using declarative languages. DRIVER takes as input declarative networking specifications written in the Network Datalog (NDlog) query language, and maps that automatically into logical specifications that can be directly used in existing theorem provers to validate protocol correctness. As an alternative approach, network designer can supply a component-based model of their routing design, automatically generate PVS specifications for verification and subsequent compilation into veriffied declarative network implementations. We demonstrate the use of DRIVER for synthesizing and verifying a variety of well-known network routing protocols.Publication Reduction-Based Formal Analysis of BGP Instances(2012-01-01) Wang, Anduo; Talcott, Carolyn; Gurney, Alexander JT; Loo, Boon Thau; Scedrov, AndreToday’s Internet interdomain routing protocol, the Border Gateway Protocol (BGP), is increasingly complicated and fragile due to policy misconfigurations by individual autonomous systems (ASes). These misconfigurations are often difficult to manually diagnose beyond a small number of nodes due to the state explosion problem. To aid the diagnosis of potential anomalies, researchers have developed various formal models and analysis tools. However, these techniques do not scale well or do not cover the full set of anomalies. Current techniques use oversimplified BGP models that capture either anomalies within or across ASes, but not the interactions between the two. To address these limitations, we propose a novel approach that reduces network size prior to analysis, while preserving crucial BGP correctness properties. Using Maude, we have developed a toolkit that takes as input a network instance consisting of ASes and their policy configurations, and then performs formal analysis on the reduced instance for safety (protocol convergence). Our results show that our reduction based analysis allows us to analyze significantly larger network instances at low reduction overhead.Publication A Reduction-Based Approach Towards Scaling Up Formal Analysis of Internet Configurations(2013-01-01) Wang, Anduo; Gurney, Alexander JT; Han, Xianglong; Cao, Jinyan; Loo, Boon T; Talcott, Carolyn; Scedrov, AndreThe Border Gateway Protocol (BGP) is the single inter-domain routing protocol that enables network operators within each autonomous system (AS) to influence routing decisions by independently setting local policies on route filtering and selection. This independence leads to fragile networking and makes analysis of policy configurations very complex. To aid the systematic and efficient study of the policy configuration space, this paper presents network reduction, a scalability technique for policy-based routing systems. In network reduction, we provide two types of reduction rules that transform policy configurations by merging duplicate and complementary router configurations to simplify analysis. We show that the reductions are sound, dual of each other and are locally complete. The reductions are also computationally attractive, requiring only local configuration information and modification. We have developed a prototype of network reduction and demonstrated that it is applicable on various BGP systems and enables significant savings in analysis time. In addition to making possible safety analysis on large networks that would otherwise not complete within reasonable time, network reduction is also a useful tool for discovering possible redundancies in BGP systems.