Methods, a client entity, network entities, a system, and a computer program product perform authentication between a client entity and a network. The network includes at least a bootstrapping server function entity and a network application function entity. The client entity is not able to communicate with both of the network entities in a bidirectional manner. The 3GPP standard Ub reference point between the client entity and the bootstrapping server function entity is not utilized for authentication purposes, such as authentication using GAA functionality for unidirectional network connections.