Alibaba Cloud builds L2TP

There are currently 4 types of VPN tunneling protocols: Point-to-Point Tunneling Protocol PPTP, Layer 2 Tunneling Protocol L2TP, Network Layer Tunneling Protocol IPSec and SOCKS v5. We only introduce Point-to-Point Tunneling Protocol PPTP here.

PPTP协议原理
PPTP使用一个TCP连接对隧道进行维护，使用通用路由封装（GRE）技术把数据封装成PPP数据桢通过隧道传送。可以对封装PPP桢中的负载数据进行加密或压缩。

环境准备

centos7服务器 （这里我使用阿里云，vpc专有网络。）

windows10 客户端 （测试***使用）

1、检查服务器是否支持PPTP协议
        modprobe ppp-compress-18 && echo ok

2.关闭防火墙
    systemctl stop firewalld.service
    systemctl disable firewalld.service

3. Update yum source, install software package

   yum install epel-release -y

   yum install ppp pptpd ppp-devel iptables iptables-services -y

4. Modify the configuration file
vim /etc/pptpd.conf
localip 192.168.0.1 #Intranet ip address (the server's eth0 network card address, not the server public network address)
remoteip 192.168.0.10-150 #Customize the network segment assigned to the client

vim /etc/ppp/options.pptpd
name pptpd
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
ms-dns 223.5.5.5
ms-dns 114.114.114.114
proxyarp
lock
nobsdcomp
novj
novjccomp
nologfd
logfile /var/log/pptpd.log

vim /etc/ppp/chap-secrets    配置账号、密码
#在文件的末尾行添加自己的登录账号，添加登录账号的格式：用户名 pptpd 密码 *

test pptpd 12345 *

5. Configure IPv4 forwarding

echo 'net.ipv4.ip_forward=1' >>/etc/sysctl.conf

sysctl -p executes the command to take effect immediately

6. Configure the firewall and enable data routing (a critical step, without firewall configuration, network access cannot be achieved)

iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED -j ACCEPT
iptables -A INPUT -p icmp -m icmp --icmp-type 8 -j ACCEPT
iptables -A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -m tcp --dport 1723 -j ACCEPT
iptables -A INPUT -p tcp -m tcp --dport 47 -j ACCEPT
iptables -A INPUT -p gre -j ACCEPT

iptables -t nat -A POSTROUTING -s 172.16.1.0/24 -o eth0 -j MASQUERADE

service iptables save save configuration
systemctl restart iptables restart firewall

配置阿里云白名单
开启TCP的1723端口
开启GRE协议

修改 vim /etc/ppp/ip-up 文件

重启服务
systemctl restart pptpd
systemctl restart  iptables

7. Configure the windows10 client

Intranet address to connect to Alibaba Cloud server