iptables 的端口转发

iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080
把发往本地的 80 端口的数据转发到 8080 端口。

iptables -t nat -A OUTPUT -p tcp --dport 80 -j REDIRECT --to-ports 8080
从本地80端口发出的数据转发到8080端口。

扩展一下，把脚本保存为 /etc/ini.d/ipt ，可以使用 sudo /etc/init.d/ipt {start|stop|restart} 来执行
#! /bin/sh
#     This program is used to use start my iptables.
#History :
#  11/05/2007 12:54:05   comet
PATH=/sbin:/bin:/usr/sbin:/usr/bin

case "$1" in
  start)
        echo -n "Staring to write your Iptbales:..."
        iptables -t nat -A PREROUTING -p tcp --dport 80 -j REDIRECT --to-ports 8080
        echo "Ok"

;;
  stop)
        echo -n "Cleaning your Iptables:..."
        /sbin/iptables -F -t nat
        /sbin/iptables -X -t nat
        /sbin/iptables -Z -t nat
        echo "Ok"
;;
  restart)
        echo -n "Cleaning your Iptables:..."
        /sbin/iptables -F -t nat
        /sbin/iptables -X -t nat
        /sbin/iptables -Z -t nat
        echo "Ok"
        echo -n "Staring to write your Iptbales:..."
        /sbin/iptables -t nat -A PREROUTING -p tcp  --dport 6000 -j DNAT --to-destination $Localip:5900
        echo "Ok"
;;
*)
        echo "Usage: $0          {start|stop|restart}"
esac

exit 0

把发往本地的 6000 端口的数据转发到 5900 端口，用来绕过端口封锁