1. A method of controlling access by a network user to one or more resources of an information network comprising the steps of: (a) establishing a security association among users and resources of said information network; (b) selectively permitting a network user to conduct data communications with respect to a network resource in accordance with said security association; (c) monitoring activity associated with said network user's conducting data communications with respect to said network resource in step (b); and (d) controllably modifying one or more security relationships contained in the security association that has been established in step (a), in dependence upon one or more characteristics of said activity monitored in step (b), in a manner that affects the ability of said network user to conduct data communications with respect to a network resource.