Wrong interface, you need to do something like TCP_CORK for udp, then the user does a write() of the headers then a sendfile() then an uncork. When the uncork happens you push the accumulated SKB to be transmitted. - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html