解决方法
http://www.bjou.de/blog/2008/05/howto-copyteeclone-network-traffic-using-iptables/
或http://www.netfilter.org/projects/patch-o-matic/pom-external.html
iptables -A PREROUTING -t mangle -p udp --dport 7 -j ROUTE --gw 1.2.3.4 --tee iptables -A POSTROUTING -t mangle -p udp --sport 7 -j ROUTE --gw 1.2.3.4 --tee
