add netfilter.c
readd netfilter
Revert "add netfilter.c"

This reverts commit 6110c507cb709175f1555137643b8890da1ab4f7.
Revert "Revert "add netfilter.c""

This reverts commit 0ea9b2e55bff34025cc0a6fc08c9f1b30700c424.
add txt and txt2
modify txt
modify txt2
change txt to origin version
modify txt2