In this paper, we study both the jamming capability of the cognitiveradio-based jammers and the anti-jamming capability of the cognitive radio networks. We first setup the models of cognitive-radiobased jammers and the cognitive radio network transmissions. We then analyze various jamming attack strategies where the jammer spends various powers in order to jam various transmission slots of the cognitive radio networks. Average throughput and jamming probability are derived and verified by simulations. Strength and weakness of jammer and cognitive radio networks are then discussed, which will be useful to guide the anti-jamming cognitive radio network design.