Refereed paper: A Fundamental Framework for Network Security Towards Enabling Security on Demand in an ATM Network

The traditional, certification based approach attempts to guarantee the security of a network through risk analysis that involves the static analysis of the risks, threats, resource availability, cost, and other parameters. Certified networks are generally confined to a limited domain and, as a result, they are isolated, costly, and under-utilized. This paper integrates the recently introduced fundamental framework for network security with the fundamental and unique characteristics of ATM networks towards a new paradigm-user level security on demand. The framework approach has been adopted by the US National Security Agency as the basis for its Network Rating Model. The framework consists of eight perspectives and nine attributes. The perspectives, termed pillars in this paper, individually provide orthogonal views of network security and collectively constitute a comprehensive stable structure that supports the total network security. The attributes refer to the inherent characteristics of a secure network. The framework provides a basis to address, fundamentally, every weakness in a given network. It also enables the understanding of the security posture of an individual network, in a comprehensive manner, the comparative evaluation of the security of two or more networks, and the determination of the resulting security of a composite network that is formed from connecting two or more networks with known security. In the proposed security on demand approach, the security posture of every node and link is computed, utilizing the framework. Under call setup, the ATM network allows the system to configure, i.e. first project and then verify through propagating a setup message containing a DTL (designated transit list), a route from the source to the destination, including every intermediate ATM node and link, that meets the requirements of every user. Every user specifies the appropriate elements of a security matrix that represents the desired security requirements, in addition to the usual bandwidth and other quality of service (QoS) requirements. Traffic is launched when the call setup succeeds, otherwise, the call fails. Thus, the approach is consistent with the basic characteristics of, is fundamentally the most logical approach to security in, and offers comprehensive security in ATM networks. It also views security as a distributed network resource and allocates it to each user efficiently, based on demand and dictated by the need. The approach has been integrated into the call admission control (CAC) algorithm of the ATM Forum proposed Private Network-Network Interface (PNNI), modeled for a representative, 50-node ATM network, and an asynchronous distributed simulation is executed on a testbed of 25+ Pentium workstations under Linux, configured as a loosely-coupled parallel processor. While the success of the implementation validates the approach, the asynchronous distributed simulation closely resembles an operational ATM network. Performance results, obtained utilizing stochastic and representative input traffic, reveal that the overhead of integrating security into CAC is negligible.