在工作中经常会遇到vpc网络，内网所有机器通过唯一一台对外的proxy机器进行共享上网，这里记录一下如何做好端口转发和管理。

  1. 展示所有nat表规则 以编号标注
root@jumper:~# iptables -L -t nat --line-number
Chain PREROUTING (policy ACCEPT)
num  target     prot opt source               destination
1    DNAT       tcp  --  anywhere             anywhere             tcp dpt:EtherNet/IP-1 to:192.168.1.3:2538
2    DNAT       tcp  --  anywhere             anywhere             tcp dpt:ssh to:192.168.1.2:2538
3    DNAT       tcp  --  anywhere             anywhere             tcp dpt:7687 to:192.168.1.3:7687
4    DNAT       tcp  --  anywhere             anywhere             tcp dpt:dxspider to:192.168.1.3:8873
Chain INPUT (policy ACCEPT)
num  target     prot opt source               destination
Chain OUTPUT (policy ACCEPT)
num  target     prot opt source               destination
Chain POSTROUTING (policy ACCEPT)
num  target     prot opt source               destination
1    SNAT       tcp  --  anywhere             newdev.my-domain.com  tcp dpt:EtherNet/IP-1 to:192.168.1.1
2    SNAT       tcp  --  anywhere             dev.my-domain.com     tcp dpt:vnwk-prapi to:192.168.1.1
3    SNAT       tcp  --  anywhere             dev.my-domain.com     tcp dpt:ssh to:192.168.1.1
4    SNAT       tcp  --  anywhere             newdev.my-domain.com  tcp spt:7687 to:192.168.1.1
5    SNAT       tcp  --  anywhere             newdev.my-domain.com  tcp spt:dxspider to:192.168.1.1
6    SNAT       all  --  192.168.1.0/24       anywhere             to:192.168.1.1
  1. 删除其中一个规则
// 删除nat表PREROUTING中的第一个规则
iptables -t nat -D PREROUTING 1
// 删除nat表中POSTROUTING中的第一个规则
iptables -t nat -D POSTROUTING 1
  1. 添加转发规则
iptables -t nat -A PREROUTING -p tcp -m tcp --dport 2233 -j DNAT --to-destination 192.168.1.2:2538
iptables -t nat -A POSTROUTING -d 192.168.1.2/32 -p tcp -m tcp --dport 2233 -j SNAT --to-source 192.168.1.1