Method of handling the contents of TCP packets on router via netfilter

This paper researches on how to deal with the contents of the packets via the technology of netfilter on the router device. And this page mainly introduced the architecture of netfilter, the firmware of router, the method of netfilter programming and transplanting as well as the realization of the TCP packet´s addition, deletion, modification, detection function. Finally, list an example of installing a netfilter module on the router device and its experimental result to demonstrate that the application of this scheme is feasible.