Finally, compromise of the weakest host in a networked system allows that host to be used as a stepping-stone to compromise other more protected hosts. Requirements definitions for resistance, recognition, recovery, and adaptation and evolution services help select survivability strategies to deal with these phases of intrusion. Some strategies, such as firewalls, are the product of extensive research and development and currently are used extensively in bounded networks. New survivability strategies are emerging to respond to the unique challenges of unbounded networks. Resistance Service Requirements.
Resistance is the capability of a system to deter attacks.
Resistance is thus important in the penetration and exploration phases of an attack, before actual exploitation. Current strategies for resistance include the use of firewalls, authentication, and encryption. Diversification is a resistance strategy that will likely become more important for unbounded networks. Requirements for diversification must define planned variation in survivable system function, structure, and organization, and the means for achieving it. Diversification is intended to create a moving target and render ineffective the accumulation of system knowledge as an intrusion strategy.