ros_pppoe是拨号的interface

chain=srcnat action=masquerade out-interface=ros_pppoe log=no log-prefix=””

端口映射，三个端口根据自己的情况来
chain=dstnat action=dst-nat to-addresses=192.168.5.10 protocol=tcp in-interface=ros_pppoe dst-port=38945,12136,42573 log=no log-prefix=””
chain=dstnat action=dst-nat to-addresses=192.168.5.10 protocol=udp in-interface=ros_pppoe dst-port=38945,12136,42573 log=no log-prefix=””

原来我的ros一直没有 out-interface=ros_pppoe，加上这个，甜糖就可以了。