Techniques are described for dynamically inserting filters into a forwarding path of a router in response to a received filter description. For example, a first router may receive a generic filter description, and process the generic filter description to generate machine instructions executable by forwarding hardware. The forwarding hardware, which may be a forwarding engine or an interface card, executes the machine instructions to implement the dynamic filter. The router, for instance, may filter packet flows of a device sourcing a network disturbance, such as a denial of service (DoS) attack by applying the dynamic filter to the packet flows. The router may further forward the filter description to neighboring routers to filter the packet flows closer to the source.