物理机：
Wan : xxx.xxx.xxx.xxx
Lan : 192.168.122.1

虚拟机：
Lan : 192.168.122.2

物理机 iptables :

iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 2222 -j DNAT --to-destination 192.168.122.2:22
iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j DNAT --to-destination 192.168.122.2
iptables -t nat -A POSTROUTING -d 192.168.122.2 -p tcp -j SNAT --to-source 192.168.122.1