An allowed client server, that is authorized to access a resource server over a given port, receives a client request, from a client computing system, to access the resource server. The allowed client server authenticates and authorizes the request, using an authentication and authorization mechanism, and selects a port with which to communicate with the client computing system. The identity of that port is provided to the client computing system, and a port forwarding mechanism forwards traffic between the client computing system and the resource server, through the client-facing port and to the given port on the resource server.