In this paper, we propose Scalable and Self-configurable Eduroam by using DHT, in order to improve the scalability of Eduroam and make it self-configurable in case of joining/leaving node operation takes place frequently. In the proposed system, RADIUS servers run on DHT substrate and they form a DHT-based RADIUS network. A RADIUS server manages a single domain. It uses the domain name as a key and uses its IP address and port number as the concatenated string for a value in the DHT- based network. In the DHT-based RADIUS network, node joins and leaves are handled automatically by obeying the updating rules of DHT. When a client sends an authentication request, RADIUS server which receives the request will forward it to the corresponding RADIUS server through a DHT lookup operation with the target domain name of the request.