It has been approved that the message checking services of Internet protocols possess the capacity of parasitic computing for some non-deterministic polynomial (NP)-complete problems. Inspired by this thought, we wonder how to dig storage capacity over the Internet by means of the message processing mechanism of protocols without extra cost. As data packets may travel over the network for a period of time and return to the source site circularly, a large capacity and dynamic parasitic storage could be created by establishing the mechanism to guarantee a certain amount of data packets being sent and received repeatedly among network nodes. However, parasitic storage may affect the network to some extent and vary itself with the fluctuation of the network. To analyze the interaction between them, an analysis model has been constructed. With this model, we have explored the parasitic storage impacts on network and the characteristics of parasitic storage over complex network in the sense of probability.