本教程仅仅适用于Xen或KVM VPS,不适用于Openvz VPS，安装之前请确定自己是否是符合标准！

1. 下载vpn(CentOS6专用)一键安装包
#wget http://www.hi-vps.com/shell/vpn_centos6.sh
#chmod a+x vpn_centos6.sh
2. 运行一键安装包
#bash vpn_centos6.sh

会有三个选择:

1. 安装VPN服务
2. 修复VPN
3. 添加VPN用户首先输入1，回车,VPS开始安装VPN服务. VPN服务安装完毕后会默认生成一个用户名为vpn，密码为随机数的用户来。

3. 添加VPN用户
#bash vpn_centos6.sh选择3，然后输入用户名和密码,OK

4. 修复VPN服务
如果VPN拨号发生错误,可以试着修复VPN,然后重启VPS
#bash vpn_centos6.sh
选择2，然后reboot

下面是具体的脚本：
#!/bin/bash

function installVPN(){
echo “begin to install VPN services”;
#check wether vps suppot ppp and tun

yum remove -y pptpd ppp
iptables –flush POSTROUTING –table nat
iptables –flush FORWARD
rm -rf /etc/pptpd.conf
rm -rf /etc/ppp

arch=`uname -m`

wget http://www.hi-vps.com/downloads/dkms-2.0.17.5-1.noarch.rpm
wget http://wty.name/linux/sources/kernel_ppp_mppe-1.0.2-3dkms.noarch.rpm
wget http://www.hi-vps.com/downloads/kernel_ppp_mppe-1.0.2-3dkms.noarch.rpm
wget http://www.hi-vps.com/downloads/pptpd-1.3.4-2.el6.$arch.rpm
wget http://www.hi-vps.com/downloads/ppp-2.4.5-17.0.rhel6.$arch.rpm

yum -y install make libpcap iptables gcc-c++ logrotate tar cpio perl pam tcp_wrappers
rpm -ivh dkms-2.0.17.5-1.noarch.rpm
rpm -ivh kernel_ppp_mppe-1.0.2-3dkms.noarch.rpm
rpm -qa kernel_ppp_mppe
rpm -Uvh ppp-2.4.5-17.0.rhel6.$arch.rpm
rpm -ivh pptpd-1.3.4-2.el6.$arch.rpm

mknod /dev/ppp c 108 0
echo 1 > /proc/sys/net/ipv4/ip_forward
echo “mknod /dev/ppp c 108 0″ >> /etc/rc.local
echo “echo 1 > /proc/sys/net/ipv4/ip_forward” >> /etc/rc.local
echo “localip 172.16.36.1″ >> /etc/pptpd.conf
echo “remoteip 172.16.36.2-254″ >> /etc/pptpd.conf
echo “ms-dns 8.8.8.8″ >> /etc/ppp/options.pptpd
echo “ms-dns 8.8.4.4″ >> /etc/ppp/options.pptpd

pass=`openssl rand 6 -base64`
if [ “$1” != “” ]
then pass=$1
fi

echo “vpn pptpd ${pass} *” >> /etc/ppp/chap-secrets

iptables -t nat -A POSTROUTING -s 172.16.36.0/24 -j SNAT –to-source `ifconfig | grep ‘inet addr:’| grep -v ’127.0.0.1′ | cut -d: -f2 | awk ‘NR==1 { print $1}’`
iptables -A FORWARD -p tcp –syn -s 172.16.36.0/24 -j TCPMSS –set-mss 1356
service iptables save

chkconfig iptables on
chkconfig pptpd on

service iptables start
service pptpd start

echo “VPN service is installed, your VPN username is vpn, VPN password is ${pass}”

}

function repaireVPN(){
echo “begin to repaire VPN”;
mknod /dev/ppp c 108 0
service iptables restart
service pptpd start
}

function addVPNuser(){
echo “input user name:”
read username
echo “input password:”
read userpassword
echo “${username} pptpd ${userpassword} *” >> /etc/ppp/chap-secrets
service iptables restart
service pptpd start
}

echo “which do you want to?input the number.”
echo “1. install VPN service”
echo “2. repaire VPN service”
echo “3. add VPN user”
read num

case “$num” in
[1] ) (installVPN);;
[2] ) (repaireVPN);;
[3] ) (addVPNuser);;
*) echo “nothing,exit”;;
esac