An access control system for a computing environment in which a number of processing nodes are interconnected to one another via an interconnection system. Multiple program applications, each made up of a number of application components, are installed in the environment, such that their components may be distributed among the various processing nodes of the platform. A set of rules is established, indicating allowed inter-node communications between the application components, and those rules are mapped onto a set of logic in the platform. The logic may be embodied in various forms, such as packet-filtering logic in a network interconnect switch, or firewall logic in a processing node. In turn, when an application component on one node attempts to communication with another application component on another node, a determination can be made whether the communication is allowed and, if the communication is not allowed, the communication can be blocked.