Dynamic Packet Forwarding Verification in SDN

Like traditional IP networking, the emerging Software-Defined Networking (SDN) technology is vulnerable to sophisticated attacks against packets and their forwarding behaviors. However, existing proposals of packet forwarding verification for IP networking cannot be directly applied to the current SDN deployment due to the limited functionalities and resources in commercial off-the-shelf (COTS) SDN switches. We propose DynaPFV, a dynamic packet forwarding verification mechanism that is capable of detecting various sophisticated attacks against packet forwarding. DynaPFV leverages the controllability of SDN to examine both packets and flow statistics across a network of switches to detect violation of packet integrity and forwarding behaviors. To mitigate the verification overhead, DynaPFV dynamically adjusts the rates of packet sampling and flow statistics collection based on the prior detection results in order to preserve the verification accuracy. Furthermore, DynaPFV makes changes to the SDN controller only, and is directly deployable atop COTS SDN switches without modifications. We conduct theoretical analysis on the trade-off between performance and accuracy in our dynamic verification approach. We further prototype DynaPFV using the open-source Floodlight controller, and evaluate our DynaPFV prototype using Mininet simulations and hardware testbed experiments. DynaPFV achieves over 97 percent of verification accuracy only with less than 5 percent of throughput degradation and less than 10 percent of additional forwarding delays.