iptables进行端口转发

需求外网访问内网的WEB服务器

我的测试环境：VMware workstation + 2台 Ubuntu 12.04.5 LTS 版本的。
转发外网服务器2个网卡一个192.168.31.206，一个10.10.100.52 )
内网服务器：10.10.100.51

转发服务器配置

iptables -t nat -A PREROUTING -d 192.168.31.206 -p tcp --dport 80 -j DNAT --to-destination 10.10.100.51:80
iptables -t nat -A OUTPUT -d 192.168.31.206 -p tcp --dport 80 -j DNAT --to-destination 10.10.100.51:80//本机访问需要添加OUTPUT 

iptables -t nat -A POSTROUTING -j MASQUERADE

//查看规则
root@ubuntu:/home/hu# iptables -t nat --list --lin
Chain PREROUTING (policy ACCEPT)
num  target     prot opt source               destination         
1    DNAT       tcp  -- anywhere 192.168.31.206 tcp dpt:http to:10.10.100.51:80

Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination          
1    DNAT       tcp  -- anywhere 192.168.31.206 tcp dpt:http to:10.10.100.51:80 

Chain POSTROUTING (policy ACCEPT)
num  target     prot opt source               destination         
1    MASQUERADE all  -- anywhere anywhere 

//删除规则
iptables -t nat -D PREROUTING 1   //序号从1 开始，后边以此+1.