This work discusses a conceptual model for automatic acquisition and processing of knowledge about users and devices in computer networks. It employs autonomous agents for distributed knowledge management and integrates them into an autonomic middleware component. Agents grouped into distributed communities act as mediators between users, devices, and network resources. Communicating between each other they make decisions on whether a certain user or device can be given access to a requested resource. In other words, agents in our system perform user/device authentication, authorisation, and maintenance of user credentials.