Abstract Protocol-Oblivious Forwarding (POF) is a groundbreaking technology that enables a protocol-independent data plane for the future Software-Defined Networking (SDN). Compared to OpenFlow and P4, POF provides more generality and flexibility in the data plane, but at a cost of additional complexity in the control plane. To overcome such complexity, in this paper we present PNPL, the first control plane programming framework over the POF SDN data plane. PNPL provides an easy-to-use programming paradigm that includes a header specification language and a set of protocol-agnostic programming APIs. With PNPL, a programmer can arbitrarily define network protocols, and compose network policies over the self-defined protocols with high-level abstractions. PNPL’s runtime system takes the user program as input, automatically produces and maintains forwarding pipelines in POF switches. The pipeline efficiently parses the self-defined protocol headers and enforces the programmer’s network policy. We have implemented a PNPL prototype, and experiment with existing and novel protocols and a number of network applications. We show that PNPL can effectively facilitate network innovations by simplifying programming over novel protocols, producing and maintaining forwarding pipelines of high quality; compared to P4, PNPL does not require a device configuration phase, and improves network performance by significantly reducing the packet parsing overhead.