VPN的智能加速原理

参考的是云梯的智能加速方案。原理其实很简单，就是对国内站点网段走默认网关，其他的才会走VPN.

所以我们首先需要挑选出来国内站点的网段，ipip.net的工作者在 github 上整理出了许多国内站点网段。

然后修改vpn设置：每次启动的时候增加路由规则，将这些国内网段走默认网关，关闭的时候将这些路由规则移除。每个步骤对应的脚本看下面这段代码

function fedora_install() {
  cp $SCRIPTDIR/data/ip-pre-up /etc/NetworkManager/dispatcher.d/pre-up.d/ip-pre-up
  chmod +x /etc/NetworkManager/dispatcher.d/pre-up.d/ip-pre-up

  cp $SCRIPTDIR/data/ip-up /etc/ppp/ip-up.local
  chmod +x /etc/ppp/ip-up.local

  cp $SCRIPTDIR/data/ip-down /etc/ppp/ip-down.local
  chmod +x /etc/ppp/ip-down.local
}

function ubuntu_install() {
  cp $SCRIPTDIR/data/ip-pre-up /etc/ppp/ip-pre-up
  chmod +x /etc/ppp/ip-pre-up

  cp $SCRIPTDIR/data/ip-up /etc/ppp/ip-up.d/ip-up
  chmod +x /etc/ppp/ip-up.d/ip-up

  cp $SCRIPTDIR/data/ip-down /etc/ppp/ip-down.d/ip-down
  chmod +x /etc/ppp/ip-down.d/ip-down
}

`/etc/ppp/ip-pre-up` 应该是在vpn开启之前调用，这样可以获得默认网关.

#!/bin/bash
# Generate on 2017-02-03 04:38 by VPNCloud
export PATH="/bin:/sbin:/usr/sbin:/usr/bin"

OLDGW=`ip route show | grep '^default' | sed -e 's/default via \([^ ]*\).*/\1/'`

if [ $OLDGW == '' ]; then
    exit 0
fi

echo $OLDGW > /tmp/vpn_oldgw

vpn启动之后执行 `/etc/ppp/ip-ip` . 执行如下命令添加路由规则

#!/bin/bash
# Generate on 2017-02-03 04:38 by VPNCloud
export PATH="/bin:/sbin:/usr/sbin:/usr/bin"

OLDGW=`cat /tmp/vpn_oldgw`

route add -net 1.0.1.0 netmask 255.255.255.0 gw $OLDGW
route add -net 1.0.2.0 netmask 255.255.254.0 gw $OLDGW
route add -net 1.0.8.0 netmask 255.255.248.0 gw $OLDGW
route add -net 1.0.32.0 netmask 255.255.224.0 gw $OLDGW
route add -net 1.1.0.0 netmask 255.255.255.0 gw $OLDGW

vpn关闭的时候执行 `/etc/ppp/ip-down` 把之前添加的路由规则移除

#!/bin/bash
# Generate on 2017-02-03 04:38 by VPNCloud
export PATH="/bin:/sbin:/usr/sbin:/usr/bin"

OLDGW=`cat /tmp/vpn_oldgw`


route del -net 1.0.1.0 netmask 255.255.255.0
route del -net 1.0.2.0 netmask 255.255.254.0