fixed bug: forgot to free sk_buff with unknown ip protocol

Signed-off-by: jason-foo <fujianshuang@gmail.com>
remove useless test script

Signed-off-by: jason-foo <fujianshuang@gmail.com>
Added a kernel module for test

This module just filters ip and arp packets, but our implementation is base on
data link socket.
You can block packets form the original protocol statck in kernel, and test if
our version works.

Signed-off-by: jason-foo <fujianshuang@gmail.com>