通过iptable进行流量转发

背景：服务器迁移，移动端写死的IP，故需兼容两个IP

1、shell脚本

#!/bin/bash

OLD_IP=A1.A2.A3.A4
NEW_IP=B1.B2.B3.B4
OLD_PORT=12345
NEW_PORT=12345
# enable IP forwarding
echo 1 > /proc/sys/net/ipv4/ip_forward

# redirect the traffic on port $PORT
iptables -t nat -A PREROUTING -p tcp --dport $OLD_PORT -j DNAT --to-destination $NEW_IP:$NEW_PORT
iptables -t nat -A POSTROUTING -p tcp -d $NEW_IP --dport $NEW_PORT -j SNAT --to-source $OLD_IP


# finally, rewrite the IPs (MASQUERADE)
iptables -t nat -A POSTROUTING -j MASQUERADE

service iptables stop

service iptables save

service iptables restart

 

2、查询

• 查询nat规则表

#PRETOURING链下NAT表，默认查询FILTER表
iptables -t nat -L PREROUTING

3、参考

• http://blog.sina.com.cn/s/blog_5f6399bc0102viis.html
• http://blog.sina.com.cn/s/blog_157cec61e0102y3ya.html