in NF_BR_FORWARD hook function,
I get a sk_buff * parameter called skb.
I use the skb and skb_copy_expand to create a new sk_buff * called new_skb,
the new_skb has the same ip header and tcp header with skb,
then send it out using dev_queue_xmit,
dev_queue_xmit returnes successful,
and in NF_BR_FORWARD hook function I return NF_DROP.
but at the peer, can not receive the packet sent.