最近突然觉得买的云服务器没啥用，都在那里闲着。想着搞点事情，不要浪费资源。然后，就想部署个vpn试试看。可惜最后遇到了一个暂时无法解决的问题。在此写篇文章记录下，如果有人看到的话有什么好的解决办法可以一起探讨下。

环境：

Linux： OpenCloudOS 8.6（Centos8）

所需软件

openvpn（服务器端）： yum -y install openvpn
easy-rsa（证书生成管理）： yum -y install easy-rsa
iptables-service（流量转发）： yum -y install iptables-service

步骤

服务器端

1. 生成证书

复制一份easy-rsa到/etc/openvpn目录下

cp -r /usr/share/easy-rsa/ /etc/openvpn/easy-rsa

复制easy-rsa配置文件到/etc/openvpn/easy-rsa/3.0.8目录下,并重命名为vars

cp -r /usr/share/doc/easy-rsa/vars.example /etc/openvpn/easy-rsa/3.0.8/vars

初始化证书
如果以前的证书不要了,要从头开始创建证书就要从这一步开始

cd /etc/openvpn/easy-rsa/3.0.8
./easyrsa init-pki

创建根证书,会提示设置密码,此处我用nopass参数选择不要密码,

./easyrsa build-ca nopass

创建server端证书和私钥文件

./easyrsa gen-req server nopass

给server端证书签名,提示confirm request details:时,输入yes

./easyrsa sign server server

创建dh文件,秘钥交换算法

./easyrsa gen-dh

创建tls认证秘钥

openvpn –genkey –secret ta.key

拷贝证书文件到openvpn目录下:

mkdir /etc/openvpn/certs
cp ./pki/ca.crt /etc/openvpn/certs/
cp ./pki/dh.pem /etc/openvpn/certs/
cp ./pki/issued/server.crt /etc/openvpn/certs
cp ./pki/private/server.key /etc/openvpn/certs
cp ta.key /etc/openvpn/certs

创建server配置文件

拷贝配置文件模板

cp /usr/share/doc/openvpn/sample/sample-config-files/server.conf /etc/openvpn/

修改配置文件

cd /etc/openvpn
vim server.conf

#监听本机ip地址(这里填本机地址,云服务器上填的是内网地址不是公网地址，切记)local 0.0.0.0#监控本机端口号port 1194#指定采用的传输协议，可以选择tcp或udpproto tcp#指定创建的通信隧道类型，可选tun或tap,window服务器必须是tapdev tun#指定CA证书的文件路径ca /etc/openvpn/certs/ca.crt#指定服务器端的证书文件路径cert /etc/openvpn/certs/server.crt#指定服务器端的私钥文件路径key /etc/openvpn/certs/server.key#指定迪菲赫尔曼参数的文件路径dh /etc/openvpn/certs/dh.pem#指定虚拟局域网占用的IP地址段和子网掩码，不能和服务器eth0同网段server 10.8.0.0 255.255.255.0#服务器自动给客户端分配IP后，客户端下次连接时，仍然采用上次的IP地址(第一次 分配的IP保存在ipp.txt中，下一次分配其中保存的IP)。ifconfig-pool-persist ipp.txt#自动推送客户端上的网关及DHCP,此项开启了流量转发,有这项才能使用服务器代理上 网push "redirect-gateway def1 bypass-dhcp"#OpenVPN的DHCP功能为客户端提供指定的 DNS、WINS 等push "dhcp-option DNS 114.114.114.114"#允许客户端与客户端相连接，默认情况下客户端只能与服务器相连接client-to-client#允许同一个客户端证书多次登录,看需配置#duplicate-cn#每10秒ping一次，连接超时时间设为120秒keepalive 10 120#开启TLS-auth，使用ta.key防御攻击。服务器端的第二个参数值为0，客户端的为1。tls-auth /etc/openvpn/certs/ta.key 0#加密认证算法,2.4之前是AES-256-CBCcipher AES-256-GCM#使用lzo压缩的通讯,服务端和客户端都必须配置comp-lzo#最大连接用户max-clients 100#定义运行的用户和组,openvpn用户是安装的时候系统自动创建的user openvpngroup openvpn#重启时仍保留一些状态persist-keypersist-tun#输出短日志,每分钟刷新一次,以显示当前的客户端status /var/log/openvpn-status.log#日志保存路径log /etc/openvpn/log/openvpn.loglog-append /etc/openvpn/log/openvpn.log#指定日志文件的记录详细级别，可选0-9，等级越高日志内容越详细verb 4#相同信息的数量，如果连续出现 20 条相同的信息，将不记录到日志中mute 20下面这项只能udp连接开启#explicit-exit-notify 1#设置tls最低版本为1.3,连接的客户端如果是2.4以下则配置为1.0tls-version-min 1.3

配置系统转发,需要代理上网的必须配置

允许转发

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

配置立即生效

sysctl -p

关闭firewall

systemctl stop firewalld
systemctl disable firewalld

启动iptables

systemctl enable iptables
systemctl start iptables

配置iptables转发流量,代理主要以iptables转发实现

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE

允许tcp/udp 1194通过防火墙

iptables -I INPUT -p tcp –dport 1194 -j ACCEPT
iptables -I INPUT -p udp –dport 1194 -j ACCEPT

保存规则并重启

service iptables save
systemctl restart iptables

创建启动的服务脚本文件

vim /lib/systemd/system/openvpn@.service

[Unit]Description=OpenVPN Robust And Highly Flexible Tunneling Application On %IAfter=network.target[Service]Type=notifyPrivateTmp=trueExecStart=/usr/sbin/openvpn --cd /etc/openvpn/ --config %i.conf[Install]WantedBy=multi-user.target

设置openvpn开机启动

systemctl enable openvpn@server

启动

systemctl start openvpn@server

查看状态

systemctl status openvpn@server
日志地址
/etc/openvpn/log/openvpn.log

客户端

服务器上操作

进入证书管理目录

cd /etc/openvpn/easy-rsa/3.0.8

生成客户端1的证书,客户端2依次类推

./easyrsa gen-req client1 nopass

注册客户端1的证书,要输入yes

./easyrsa sign client client1

将证书拷贝到一个目录存着

cp ./pki/issued/client1.crt /etc/openvpn/client
cp ./pki/private/client1.key /etc/openvpn/client

本地操作

下载地址： https://openvpn.net/community-downloads/

1.将client1.crt client1.key ta.key ca.crt四个文件下载到本地客户端目录的config

2.拷贝客户端sample-config目录下的client.ovpn文件到config目录下

############################################### Sample client-side OpenVPN 2.0 config file ## for connecting to multi-client server. #### This configuration can be used by multiple ## clients, however each client should have ## its own cert and key files.#### On Windows, you might want to rename this## file so it has a .ovpn extension ################################################ Specify that we are a client and that we# will be pulling certain config file directives# from the server.client# Use the same setting as you are using on# the server.# On most systems, the VPN will not function# unless you partially or fully disable# the firewall for the TUN/TAP interface.;dev tapdev tun# Windows needs the TAP-Win32 adapter name# from the Network Connections panel# if you have more than one.On XP SP2,# you may need to disable the firewall# for the TAP adapter.;dev-node MyTap# Are we connecting to a TCP or# UDP server?Use the same setting as# on the server.;proto tcpproto tcp# The hostname/IP and port of the server.# You can have multiple remote entries# to load balance between the servers.#remote my-server-1 1194remote 124.222.29.42 1194# Choose a random host from the remote# list for load-balancing.Otherwise# try hosts in the order specified.;remote-random# Keep trying indefinitely to resolve the# host name of the OpenVPN server.Very useful# on machines which are not permanently connected# to the internet such as laptops.resolv-retry infinite# Most clients don't need to bind to# a specific local port number.nobind# Downgrade privileges after initialization (non-Windows only);user nobody;group nobody# Try to preserve some state across restarts.persist-keypersist-tun# If you are connecting through an# HTTP proxy to reach the actual OpenVPN# server, put the proxy server/IP and# port number here.See the man page# if your proxy server requires# authentication.;http-proxy-retry # retry on connection failures;http-proxy [proxy server] [proxy port #]# Wireless networks often produce a lot# of duplicate packets.Set this flag# to silence duplicate packet warnings.;mute-replay-warnings# SSL/TLS parms.# See the server config file for more# description.It's best to use# a separate .crt/.key file pair# for each client.A single ca# file can be used for all clients.ca ca.crtcert client1.crtkey client1.key# Verify server certificate by checking that the# certificate has the correct key usage set.# This is an important precaution to protect against# a potential attack discussed here:#http://openvpn.net/howto.html#mitm## To use this feature, you will need to generate# your server certificates with the keyUsage set to# digitalSignature, keyEncipherment# and the extendedKeyUsage to# serverAuth# EasyRSA can do this for you.remote-cert-tls server# If a tls-auth key is used on the server# then every client must also have the key.tls-auth ta.key 1# Select a cryptographic cipher.# If the cipher option is used on the server# then you must also specify it here.# Note that v2.4 client/server will automatically# negotiate AES-256-GCM in TLS mode.# See also the data-ciphers option in the manpage#cipher AES-256-CBCcipher AES-256-GCM# Enable compression on the VPN link.# Don't enable this unless it is also# enabled in the server config file.comp-lzo# Set log file verbosity.verb 3#不保存密码auth-nocache# Silence repeating messagesmute 20#使客户端中所有流量经过VPN,所有网络连接都使用vpnredirect-gateway def1tls-version-min 1.3

3.打开openvpn

遇到问题

1、当openvpn打开的时候，WiFi会断掉
解决： 暗影精灵9无法找到解决的按钮，有同学遇到这种问题可以参考，
VPN连接成功后， 无线网络适配器会自动断开
I need to make Windows 7 STOP disabling the wifi adapter when the wired LAN is connected

目前我打算换个vpn试下，准备试下 l2tp vpn

本文参考链接：
centos8安装配置openvpn实现服务器代理上网
在Linux系统上搭建内网VPN
CentOS搭建OpenVPN
OpenVpnCentos8部署