Network-wide deployment of intrusion detection and prevention systems

Traditional efforts for scaling network intrusion detection (NIDS) and intrusion prevention systems (NIPS) have largely focused on a single-vantage-point view. In this paper, we explore an alternative design that exploits spatial, network-wide opportunities for distributing NIDS and NIPS functions. For the NIDS case, we design a linear programming formulation to assign detection responsibilities to nodes while ensuring that no node is overloaded. We describe a prototype NIDS implementation adapted from the Bro system to analyze traffic per these assignments, and demonstrate the advantages that this approach achieves. For NIPS, we show how to maximally leverage specialized hardware (e.g., TCAMs) to reduce the footprint of unwanted traffic on the network. Such hardware constraints make the optimization problem NP-hard, and we provide practical approximation algorithms based on randomized rounding.