Cloud network models have limitations in handling networking between distributed cloud resources and in providing customers the ability to control and configure networks. This paper presents a Cloud Networking Gateway (CNG) Manager for dynamic establishment of intra and inter cloud connectivity. The CNG Manager interconnects virtual machines acquired from distributed heterogeneous resources and services from multiple providers using a generic gateway. The cloud networking gateways are managed by the CNG Manager that handles allocation and configuration of the gateways according to connectivity requirements. This cloud networking solution is integrated with an operational "Cloud Broker" architecture involving multiple users and providers in order to test and validate our solution in a realistic framework