Techniques for packet classification for network routing are disclosed. In some embodiments, packet classification for network routing includes receiving packets associated with a new flow at a security controller from a network device, in which the network device performs packet forwarding; classifying the flow; and determining an action for the flow based on a policy (e.g., a security policy). In some embodiments, the network device is a Software Defined Network (SDN) network device (e.g., a packet forwarding device that supports the OpenFlow protocol or another protocol).