A novel abstraction for security configuration in virtual networks

The incessant growth of network virtualization determined the proliferation of Virtual Network Functions (VNFs), software programs that can run on general-purpose servers and that can also integrate security controls for protection from cyber-attacks. However, a high availability of VNFs may be counterproductive for the network administrators who have to select the most suitable ones to establish the security configuration of their network. On the one hand, the vendor-dependent technicalities of each VNF may cloud the security controls it can actually perform. On the other hand, VNF selection traditionally occurs before the synthesis of the virtual network graph, so it does not employ any network information and it may outcome unoptimized results. In light of these shortcomings, this paper proposes a novel security configuration workflow, based on new abstractions that we call projections. They represent the security-related operations that VNFs should perform to enforce a security policy. Thanks to these abstractions, the actual selection of the VNFs can be postponed to the moment their deployment in the physical network is actually required. In fact, projections are enough for the synthesis of the virtual security graph. This paper also proposes a two-step algorithm for computing projection chains as candidate solutions for graph synthesis. The proposed approach has been implemented as a Java framework and a set of tests have validated its applicability to real-world VNFs, correctness, scalability and optimization. These tests showed that the new security configuration workflow can achieve a significant reduction for the number of selected VNFs and their deployment cost. Specifically, in the analyzed scenario, the improvement percentages for these two parameters are 79% and 90% with respect to the worst-case strategy, while 68% and 77% with respect to a traditional more optimized configuration strategy.