一个自动搭建ipip隧道的脚本

gnawux ipip linux route scripts tunnel

场景是这样的，两台机器A和B，通过缺省路由互相可达；希望A通过B的连接出去；A的地址为动态分配，且A可能的interface不缺定，因此，上来先给点先决条件：

#!/bin/bash

default_dev="wlan0"

default_gw="192.168.12.1"

flag_nogw="false"

local_ip=192.168.12.111

thost_ip=192.168.32.214

tnet_cidr="192.168.32.0/21"

local_tun_addr="172.16.1.1"

remote_tun_addr="172.16.1.254"

tun_dev="tun9"

tun_cidr="172.16.0.0/16"

然后，想办法获取缺省路由的接口和网关地址，当然，不一定所有的缺省路由都有网关地址

# get default gw and local ip address

route -n | while read dst gw msk flag metric ref use iface

do

if [ "$dst" = "0.0.0.0" -a "$msk" = "0.0.0.0" ]

then

default_dev=$iface

if [ "$flag" = "UG" ]

then

default_gw=$gw

else

flag_nogw="true"

fi

fi

done

之后判断一下连在缺省接口上的IP地址

local_ip=$(ifconfig $default_dev | grep "inet addr"|sed -ne 's/.*inet addr:$[.0-9]\+$.*/\1/p')

然后在远程主机上启动隧道、配置路由，并设置NAT：

ssh ${thost_ip} iptunnel add ${tun_dev} mode ipip remote $local_ip local ${thost_ip}

ssh ${thost_ip} ifconfig ${tun_dev} ${remote_tun_addr}

ssh ${thost_ip} route add -net ${tun_cidr} dev ${tun_dev}

ssh ${thost_ip} iptables -t nat -A POSTROUTING -s ${local_tun_addr} -j MASQUERADE

接下来设置本机上的隧道和路由：

#setup tunnel on local machine

iptunnel add ${tun_dev} mode ipip remote ${thost_ip} local ${local_ip}

ifconfig ${tun_dev} ${local_tun_addr}

route add -net ${tun_cidr} dev ${tun_dev}

最后，改缺省路由

#setup default route rule

if [ "${flag_nogw}" = "false" ]

then

route add -net ${tnet_cidr} gw ${default_gw}

route del default gw ${default_gw}

else

route add -net ${tnet_cidr} dev ${default_dev}

route del default dev ${default_dev}

fi

route add default gw ${remote_tun_addr}

完毕。

gnawux

me!#$!@#$@#$wangxu!@#$%^&*()_me