详解Centos6.5 Openvpn的安装与配置

一、安装准备

yum -y install openssl-devel openssl
yum -y install gcc gcc-c++

二、OpenVPN服务端安装过程

1.lzo下载与安装

cd /apps  #安装目录
wget ftp://www.wudonghang.com/soft/openvpn-2.1_rc15.tar.gz #下载lzo
tar zxvf lzo-2.04.tar.gz  #解压
cd lzo-2.04
./configure ; make ; make install  #编译与安装 

2.openvpn下载与安装

cd /apps
wget http://openvpn.net/release/openvpn-2.1_rc15.tar.gz
tar zxvf openvpn-2.1_rc15.tar.gz
cd openvpn-2.1_rc15
./configure ; make ; make install

3.服务器端设置

cp -r /apps/openvpn-2.1_rc15/ /etc/openvpn #用easy-rsa生成服务器证书客户端证书 

4.初始化参数

将解压目录的easy-rsa目录复制到 /etc/openvpn下

cd /etc/openvpn/easy-rsa/2.0
./vars
source vars 

5.生成CA证书

./clean-all
./build-ca 

6.建立server key(一直回车）

./build-key-server server

7.生成diffie hellman参数

./build-dh 

8.复制ca证书，服务端证书到OpenVPN配置目录

代码如下:

cp keys/{ca.crt,ca.key,server.crt,server.key,dh1024.pem} /etc/openvpn/

9.生成client key

./build-key client1 #与server key 设置一致

如要生成多个vpn账户，则与client1一样生成其他客户端证书如

./build-key client2
./build-key client3

10.生成客户端配置文件client1.ovpn

vi /etc/openvpn/easy-rsa/2.0/keys/client1.ovpn

client
remote 192.168.80.129 1194
dev tun #说明连接方式是点对点的连接，如要以以太网的方式则可以将tun修改为tap
proto tcp
resolv-retry infinite
nobind
persist-key
persist-tun
ca ca.crt
cert client1.crt
key client1.key
ns-cert-type server
comp-lzo
route-delay 2
route-method exe
verb 3

11.打包客户端配置文件证书等

tar czf keys.tgz ca.crt ca.key client1.crt client1.csr client1.key client1.ovpn
mv keys.tgz /root 

12.创建并编辑服务器端配置文件server.conf

port 1194
proto tcp
dev tun #说明连接方式是点对点的连接，如要以以太网的方式则可以将tun修改为tap
ca /etc/openvpn/easy-rsa/2.0/keys/ca.crt
cert /etc/openvpn/easy-rsa/2.0/keys/server.crt
key /etc/openvpn/easy-rsa/2.0/keys/server.key
dh /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway"
push "route 172.18.2.0 255.255.255.0" #路由转发到内网网段
push "dhcp-option DNS 172.18.2.1"
push "dhcp-option DNS 8.8.8.8"
keepalive 10 120
comp-lzo
persist-key
persist-tun
client-to-client #如果不加则各个客户端之间将无法连接 

13.对防火墙的相关设置

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o venet0 -j MASQUERADE
iptables-save > /etc/sysconfig/iptables
sed -i 's/eth0/venet0/g' /etc/sysconfig/iptables # dirty vz fix for iptables-save
echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf

如果VPN服务器上的内网ip不是网关那么必须加上下面这一句（如果不加则客户端无法连接其他内网机器）：

代码如下:

iptables -t nat -A POSTROUTING -s 10.8.0.0/255.255.255.0 -d 172.18.2.0/255.255.255.0 -j SNAT –to-source 172.18.2.30

14.启动openvpn

/usr/local/sbin/openvpn --config /etc/openvpn/server.conf

如要设置开机启动则执行命令：

代码如下:

echo “/usr/local/sbin/openvpn --config /etc/openvpn/server.conf ” >> /etc/rc.local

也可以做服务

cp /apps/openvpn-2.1_rc15/sample-scripts/openvpn.init /etc/init.d/openvpn
chmod 700 /etc/init.d/openvpn
chkconfig --add openvpn
chkconfig --level 345 openvpn on 

service openvpn start

15.查看是否安装成功

lsof -i:1194

注意：以上是公司内网中有一台机器可以连接外网的情况，如果内网中都没有机器可连接外网，那么如果内网中该网段机器（假设为B子网网段为192.168.1.0/24）要想连接另一台也无外网ip的某个网段的机器(A ip为172.9.2.100)该怎么办呢？请往下看
找到一台可以随意设置的拥有外网ip的机器假设为C

将C设置成openVPN的服务器，然后将A和B设置为openVPN客户端

在C的配置文件中加上:

client-to-client
client-config-dir ccd
route 192.168.1.0 255.255.255.0

B在ccd中的配置为：

iroute 192.168.1.0 255.255.255.0

A在ccd中的配置为：

push "route 192.168.1.0 255.255.255.0"

B的SNAT配置：

代码如下:

iptables -t nat -A POSTROUTING -s 10.8.0.0/255.255.255.0 -d 192.168.1.0/255.255.255.0 -j SNAT –-to-source 172.9.2.100

三、openvpn客户端安装(Windows)

安装OpenVPN脚本 install_OpenVPN.sh

#!/bin/bash
# Quick and dirty OpenVPN install script
# Tested on Centos 5.x 32bit, openvz minimal CentOS OS templates
# Please submit feedback and questions at support@vpsnoc.com

# John Malkowski vpsnoc.com 01/04/2010

ip=`grep IPADDR /etc/sysconfig/network-scripts/ifcfg-venet0:0 | awk -F= '{print $2}'`

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm
rpm -iv rpmforge-release-0.3.6-1.el5.rf.i386.rpm
rm -rf rpmforge-release-0.3.6-1.el5.rf.i386.rpm

yum -y install openvpn openssl openssl-devel
cd /etc/openvpn/
cp -R /usr/share/doc/openvpn-2.2.0/easy-rsa/ /etc/openvpn/
cd /etc/openvpn/easy-rsa/2.0/
chmod +rwx *
./vars
./clean-all
source ./vars

echo -e "\n\n\n\n\n\n\n" | ./build-ca
clear
echo "####################################"
echo "Feel free to accept default values"
echo "Wouldn't recommend setting a password here"
echo "Then you'd have to type in the password each time openVPN starts/restarts"
echo "####################################"
./build-key-server server
./build-dh
cp keys/{ca.crt,ca.key,server.crt,server.key,dh1024.pem} /etc/openvpn/

clear
echo "####################################"
echo "Feel free to accept default values"
echo "This is your client key, you may set a password here but it's not required"
echo "####################################"
./build-key client1
cd keys/

client="
client
remote $ip 1194
dev tun
comp-lzo
ca ca.crt
cert client1.crt
key client1.key
route-delay 2
route-method exe
redirect-gateway def1
dhcp-option DNS 10.8.0.1
verb 3"

echo "$client" > $HOSTNAME.ovpn

tar czf keys.tgz ca.crt ca.key client1.crt client1.csr client1.key $HOSTNAME.ovpn
mv keys.tgz /root

opvpn='
dev tun
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
ca ca.crt
cert server.crt
key server.key
dh dh1024.pem
push "route 10.8.0.0 255.255.255.0"
push "redirect-gateway"
comp-lzo
keepalive 10 60
ping-timer-rem
persist-tun
persist-key
group nobody
daemon'

echo "$opvpn" > /etc/openvpn/openvpn.conf

echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o venet0 -j MASQUERADE
iptables-save > /etc/sysconfig/iptables
sed -i 's/eth0/venet0/g' /etc/sysconfig/iptables # dirty vz fix for iptables-save
echo "net.ipv4.ip_forward=1" >> /etc/sysctl.conf

/etc/init.d/openvpn start
clear

echo "OpenVPN has been installed
Download /root/keys.tgz using winscp or other sftp/scp client such as filezilla
Create a directory named vpn at C:\Program Files\OpenVPN\config\ and untar the content of keys.tgz there
Start openvpn-gui, right click the tray icon go to vpn and click connect
For support/bug reports email us at support@vpsnoc.com"

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