The commercialization of the Internet has led to a large variety of business models based on Internet technology. Therefore, the demand for standardized and efficient solutions in support of reliable, secure, open, and flexible remote and mobile service accesses has increased. Existing authentication, authorization, and accounting systems still consider dedicated cases, but lack a generic approach. More general AAA services can be built by extending existing mechanisms and protocols for access scenarios other than dialup or PPP connections. While this work is performed mainly by the IETF AAA Working Group, another approach proposed by the IRTF AAAArch Research Group is termed AAA Architecture. This article surveys the state of the art in AAA and develops a new generic policy-based approach, A/sup x/, for AAA services and beyond, considering flexible levels of various services in an Internet service model, ranging from connectivity to content services.