A distributed policy enforcement architecture for mobile ad-hoc networks (2011)

Mobile Ad-hoc Networks (MANETs) are increasingly employed in tactical military and civil rapid-deployment networks, including emergency rescue operations and ad hoc disaster-relief networks. However, this flexibility of MANETs conies at a price when MANETs are compared to wired and base station-based wireless networks: MANETs are susceptible to both insider and outsider attacks. This is mainly because of the lack of a well-defined defense perimeter preventing the effective use of wired defenses, including firewalls and intrusion detection systems. 
In this thesis, we present DIPLOMA, a. novel distributed security policy enforcement architecture that is designed specifically for MANETs. Our approach harnesses and extends the concept of network capabilities and is especially suited for mobile and heterogeneous communication environments. Our model imposes communication restrictions between MANET nodes by enforcing hop-by-hop policies in a distributed manner. We use a deny-by-default principle, allowing compromised nodes to access only authorized services. This significantly limits their ability to disrupt or even interfere with end-to-end connectivity and nodes beyond their local communication radius. 
In this thesis, we present the feasibility of the architecture using a. multitude of techniques. We define a threat model and a. security analysis based on that threat model. We conduct a. preliminary evaluation of the system using the GloMoSim simulator. Through simulations, we show that our solution incurs minimal overhead in terms of network bandwidth and latency even in the presence of cryptographic operations. Furthermore, we show that the protection remains effective even in the presence of misbehaving nodes and routing changes due to mobility. 
We also present an implementation of DIPLOMA on real systems running the Linux operating system. Our implementation works at the network layer and does not require any changes to existing applications. We identify the bottlenecks and make improvements to the system so that it works well in practice. We evaluate our system in a realistic MANET testbed Orbit. To that end, we identify ways of creating multi-hop topologies in indoor environments so that a. had node cannot interfere with every other node. Our evaluations show that the system incurs minimal overhead and protects network bandwidth and the end-hosts in the presence of attackers. 
We also extend the DIPLOMA architecture to secure multicast traffic. We use capabilities to provide a unified solution for sender and receiver access control to multicast groups, as well as to limit the bandwidth usage of the multicast groups. We have extended common multicast protocols, including ODMRP and PIM-SM, to incorporate DIPLOMA. We have implemented multicast DIPLOMA in Linux without requiring any changes to existing applications and the routing substrate. We evaluate the system in the Orbit Lab testbed as well as the GloMoSim simulator to show that the system incurs minimal overhead and protects multicast traffic in the presence of attackers. 
In this thesis, we also identify how senders and receivers can misuse capabilities by using them in multiple paths, and we provide distributed solutions for detecting those misuses. To that end, we modify the capabilities to aid in misuse detection and provide protocols for exchanging information for distributed detection. We also provide efficient algorithms for misuse detection and protocols for providing proof of misuse. Our solutions can handle privacy issues associated with the exchange of information for misuse detection. We have implemented misuse detection and recovery in DIPLOMA systems running on Linux and have conducted extensive experimental evaluation of the system in the Orbit MANET testbed. The results show that our algorithms require minimal processing and memory and that distributed detection requires a very small amount of bandwidth. We also show that our system is effective in detecting and containing multi-path misuses.