||End-to-end route control spanning a set of autonomous systems (ASes) can provide opportunities to both end users to optimize interdomain control and network service providers to increase business offerings. BGP, the de facto interdomain routing protocol, and recent interdomain proposals provide limited mechanisms for such control. We provide the first, systematic formulation of the software-defined internetworking (SDI) model, where an AS exposes a programmable in- terface to allow clients to define the interdomain routes of the network, and maintains its autonomy, by keeping the control of its export policies, to avoid fundamental violations such as valley routing. We develop a blackbox optimization algorithm to quickly find optimal export-policy-compliant end-to-end routes in SDI, and validate its efficacy using real interdomain topology. To understand the operational implication of SDI, we evaluate the privacy leakage brought by exposing an AS' available interdomain routes. Preliminary results show that a small number of neighbors or a large number of exposed RIB samples allows accurate inference on an AS' BGP selection policy, indicating a potential risk of not only SDI but the whole interdomain routing community.