OpenVPN服务器及客户端配置

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[ 2012/06/29 17:42 | by Sonic ]
本文以CentOS 6 作为OpenVPN服务器,WIN XP及WIN 7作为客户端操作系统。以下内容大量借鉴了pcman大侠的文章。在此基础上,老熊又根据实际经验改写了一些配置选项。

先说服务器端
1. 安装openvpn

openvpn不在centos默认的yum安装源内。需要先安装Fedora的EPEL源。
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-7.noarch.rpm
yum install openvpn -y


其他更多软件包来源,请看EPEL、Remi、RPMForge、RPMFusion安装介绍

2. 初始化

初始化主要是配置openvpn的config文件,并设置openvpn自动启动。
复制配置文件的样本到/etc/openvpn目录下。

[root@esojourn.org ~]# cp /usr/share/doc/openvpn-2.2.2/sample-config-files/server.conf /etc/openvpn/
[root@esojourn.org ~]#


编辑/etc/openvpn/server.conf,修改如下配置,
使用TCP协议来进行访问。打开gateway,推送dns等。
#################################################
# Sample OpenVPN 2.0 config file for            #
# multi-client server.                          #
#                                               #
# This file is for the server side              #
# of a many-clients <-> one-server              #
# OpenVPN configuration.                        #
#                                               #
# OpenVPN also supports                         #
# single-machine <-> single-machine             #
# configurations (See the Examples page         #
# on the web site for more info).               #
#                                               #
# This config should work on Windows            #
# or Linux/BSD systems.  Remember on            #
# Windows to quote pathnames and use            #
# double backslashes, e.g.:                     #
# "C:\\Program Files\\OpenVPN\\config\\foo.key" #
#                                               #
# Comments are preceded with '#' or ';'         #
#################################################

# Which local IP address should OpenVPN
# listen on? (optional)
;local a.b.c.d

# Which TCP/UDP port should OpenVPN listen on?
# If you want to run multiple OpenVPN instances
# on the same machine, use a different port
# number for each one.  You will need to
# open up this port on your firewall.
port 1194

# TCP or UDP server?
proto tcp
# proto udp

# "dev tun" will create a routed IP tunnel,
# "dev tap" will create an ethernet tunnel.
# Use "dev tap0" if you are ethernet bridging
# and have precreated a tap0 virtual interface
# and bridged it with your ethernet interface.
# If you want to control access policies
# over the VPN, you must create firewall
# rules for the the TUN/TAP interface.
# On non-Windows systems, you can give
# an explicit unit number, such as tun0.
# On Windows, use "dev-node" for this.
# On most systems, the VPN will not function
# unless you partially or fully disable
# the firewall for the TUN/TAP interface.
;dev tap
dev tun

# Windows needs the TAP-Win32 adapter name
# from the Network Connections panel if you
# have more than one.  On XP SP2 or higher,
# you may need to selectively disable the
# Windows firewall for the TAP adapter.
# Non-Windows systems usually don't need this.
;dev-node MyTap

# SSL/TLS root certificate (ca), certificate
# (cert), and private key (key).  Each client
# and the server must have their own cert and
# key file.  The server and all clients will
# use the same ca file.
#
# See the "easy-rsa" directory for a series
# of scripts for generating RSA certificates
# and private keys.  Remember to use
# a unique Common Name for the server
# and each of the client certificates.
#
# Any X509 key management system can be used.
# OpenVPN can also use a PKCS #12 formatted key file
# (see "pkcs12" directive in man page).
ca ca.crt
cert server.crt
key server.key  # This file should be kept secret

# Diffie hellman parameters.
# Generate your own with:
#   openssl dhparam -out dh1024.pem 1024
# Substitute 2048 for 1024 if you are using
# 2048 bit keys.
dh dh1024.pem

# Configure server mode and supply a VPN subnet
# for OpenVPN to draw client addresses from.
# The server will take 10.8.0.1 for itself,
# the rest will be made available to clients.
# Each client will be able to reach the server
# on 10.8.0.1. Comment this line out if you are
# ethernet bridging. See the man page for more info.
server 10.8.0.0 255.255.255.0

# Maintain a record of client <-> virtual IP address
# associations in this file.  If OpenVPN goes down or
# is restarted, reconnecting clients can be assigned
# the same virtual IP address from the pool that was
# previously assigned.
ifconfig-pool-persist ipp.txt

# Configure server mode for ethernet bridging.
# You must first use your OS's bridging capability
# to bridge the TAP interface with the ethernet
# NIC interface.  Then you must manually set the
# IP/netmask on the bridge interface, here we
# assume 10.8.0.4/255.255.255.0.  Finally we
# must set aside an IP range in this subnet
# (start=10.8.0.50 end=10.8.0.100) to allocate
# to connecting clients.  Leave this line commented
# out unless you are ethernet bridging.
;server-bridge 10.8.0.4 255.255.255.0 10.8.0.50 10.8.0.100

# Configure server mode for ethernet bridging
# using a DHCP-proxy, where clients talk
# to the OpenVPN server-side DHCP server
# to receive their IP address allocation
# and DNS server addresses.  You must first use
# your OS's bridging capability to bridge the TAP
# interface with the ethernet NIC interface.
# Note: this mode only works on clients (such as
# Windows), where the client-side TAP adapter is
# bound to a DHCP client.
;server-bridge

# Push routes to the client to allow it
# to reach other private subnets behind
# the server.  Remember that these
# private subnets will also need
# to know to route the OpenVPN client
# address pool (10.8.0.0/255.255.255.0)
# back to the OpenVPN server.
push "route 10.8.0.0 255.255.255.0"
push "route 192.168.5.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"

# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have VPN access,
# use the subdirectory "ccd" for client-specific
# configuration files (see man page for more info).

# EXAMPLE: Suppose the client
# having the certificate common name "Thelonious"
# also has a small subnet behind his connecting
# machine, such as 192.168.40.128/255.255.255.248.
# First, uncomment out these lines:
;client-config-dir ccd
;route 192.168.40.128 255.255.255.248
# Then create a file ccd/Thelonious with this line:
#   iroute 192.168.40.128 255.255.255.248
# This will allow Thelonious' private subnet to
# access the VPN.  This example will only work
# if you are routing, not bridging, i.e. you are
# using "dev tun" and "server" directives.

# EXAMPLE: Suppose you want to give
# Thelonious a fixed VPN IP address of 10.9.0.1.
# First uncomment out these lines:
;client-config-dir ccd
;route 10.9.0.0 255.255.255.252
# Then add this line to ccd/Thelonious:
#   ifconfig-push 10.9.0.1 10.9.0.2

# Suppose that you want to enable different
# firewall access policies for different groups
# of clients.  There are two methods:
# (1) Run multiple OpenVPN daemons, one for each
#     group, and firewall the TUN/TAP interface
#     for each group/daemon appropriately.
# (2) (Advanced) Create a script to dynamically
#     modify the firewall in response to access
#     from different clients.  See man
#     page for more info on learn-address script.
;learn-address ./script

# If enabled, this directive will configure
# all clients to redirect their default
# network gateway through the VPN, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the VPN
# (The OpenVPN server machine may need to NAT
# or bridge the TUN/TAP interface to the internet
# in order for this to work properly).
;push "redirect-gateway def1 bypass-dhcp"
push "redirect-gateway"
# Certain Windows-specific network settings
# can be pushed to clients, such as DNS
# or WINS server addresses.  CAVEAT:
# http://openvpn.net/faq.html#dhcpcaveats
# The addresses below refer to the public
# DNS servers provided by opendns.com.
push "dhcp-option DNS 60.195.250.225"
push "dhcp-option DNS 8.8.8.8"

# Uncomment this directive to allow different
# clients to be able to "see" each other.
# By default, clients will only see the server.
# To force clients to only see the server, you
# will also need to appropriately firewall the
# server's TUN/TAP interface.
;client-to-client

# Uncomment this directive if multiple clients
# might connect with the same certificate/key
# files or common names.  This is recommended
# only for testing purposes.  For production use,
# each client should have its own certificate/key
# pair.
#
# IF YOU HAVE NOT GENERATED INDIVIDUAL
# CERTIFICATE/KEY PAIRS FOR EACH CLIENT,
# EACH HAVING ITS OWN UNIQUE "COMMON NAME",
# UNCOMMENT THIS LINE OUT.
;duplicate-cn

# The keepalive directive causes ping-like
# messages to be sent back and forth over
# the link so that each side knows when
# the other side has gone down.
# Ping every 10 seconds, assume that remote
# peer is down if no ping received during
# a 120 second time period.
keepalive 10 120
# For extra security beyond that provided
# by SSL/TLS, create an "HMAC firewall"
# to help block DoS attacks and UDP port flooding.
#
# Generate with:
#   openvpn --genkey --secret ta.key
#
# The server and each client must have
# a copy of this key.
# The second parameter should be '0'
# on the server and '1' on the clients.
;tls-auth ta.key 0 # This file is secret

# Select a cryptographic cipher.
# This config item must be copied to
# the client config file as well.
;cipher BF-CBC        # Blowfish (default)
;cipher AES-128-CBC   # AES
;cipher DES-EDE3-CBC  # Triple-DES

# Enable compression on the VPN link.
# If you enable it here, you must also
# enable it in the client config file.
comp-lzo

# The maximum number of concurrently connected
# clients we want to allow.
;max-clients 100

# It's a good idea to reduce the OpenVPN
# daemon's privileges after initialization.
#
# You can uncomment this out on
# non-Windows systems.
;user nobody
;group nobody

# The persist options will try to avoid
# accessing certain resources on restart
# that may no longer be accessible because
# of the privilege downgrade.
persist-key
persist-tun

# Output a short status file showing
# current connections, truncated
# and rewritten every minute.
status openvpn-status.log

# By default, log messages will go to the syslog (or
# on Windows, if running as a service, they will go to
# the "\Program Files\OpenVPN\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on OpenVPN startup,
# while "log-append" will append to it.  Use one
# or the other (but not both).
;log         openvpn.log
;log-append  openvpn.log

# Set the appropriate level of log
# file verbosity.
#
# 0 is silent, except for fatal errors
# 4 is reasonable for general usage
# 5 and 6 can help to debug connection problems
# 9 is extremely verbose
verb 3

# Silence repeating messages.  At most 20
# sequential messages of the same message
# category will be output to the log.
;mute 20


vi /etc/sysctl.conf。在最下面加入如下内容。
如果是RHEL5,建议把以#屏蔽的选项全打开。是照某公司久经考验的文档写的。
据神秘的老熊分享,在RHEL6下应该把那一堆参数屏蔽。我在centos 6下,已经照此配置测试通过了。

# Added for  openvpn.   esojourn.org
net.ipv6.conf.eth0.forwarding = 1
net.ipv6.conf.default.forwarding = 1
net.ipv6.conf.all.forwarding = 1
net.ipv6.conf.lo.forwarding = 1
# net.ipv4.conf.tun0.mc_forwarding = 1
# net.ipv4.conf.tun0.forwarding = 1
# net.ipv4.conf.eth0.mc_forwarding = 1
net.ipv4.conf.eth0.forwarding = 1
# net.ipv4.conf.lo.mc_forwarding = 1
net.ipv4.conf.lo.forwarding = 1
# net.ipv4.conf.default.mc_forwarding = 1
net.ipv4.conf.default.forwarding = 1
# net.ipv4.conf.all.mc_forwarding = 1
net.ipv4.conf.all.forwarding = 1
# net.ipv4.ip_forward = 1


sysctl -p使规则生效

vi /etc/sysconfig/iptables 在最上面加下nat表
诸位新手、准新手们,千万别用天杀的setup或者system-config-firewall来配防火墙了。
血泪史啊,不多解释了。好好学基本功吧。我也在学习中。
*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
COMMIT

然后在下面*filter表里,最后一条拒绝规则前面,加上
-A FORWARD -d 10.8.0.0/24 -j ACCEPT
-A FORWARD -s 10.8.0.0/24 -j ACCEPT


service iptables restart

3. 生成服务器端证书
生成服务器端证书主要有如下几个步骤:
1. 设置环境变量
2. 生成ca文件
3. 生成cert/key文件
4. 生成dh文件

进入openvpn的对应安装目录。将所有脚本设置为可执行属性
cd /usr/share/doc/openvpn-2.2.2/easy-rsa
chmod 700 build*


vi /etc/bashrc,在最下面加上环境变量
# Add for openvpn
export KEY_CONFIG=/usr/share/doc/openvpn-2.2.2/easy-rsa/openssl.cnf
export KEY_DIR=/usr/share/doc/openvpn-2.2.2/easy-rsa/keys
export KEY_SIZE=1024
export KEY_COUNTRY=CN
export KEY_PROVINCE=BJ
export KEY_CITY=BJ
export KEY_ORG="www.esojourn.org"
export KEY_EMAIL="[email]abc@esojourn.org[/email]"


建立存放key的目录 mkdir cd /usr/share/doc/openvpn-2.2.2/easy-rsa/keys
通过clean-all生成serial和index.txt
chmod 700 clean-all
./clean-all


开始生成ca文件。需要注意的是,ca一旦生成就不能更换了,否则所有key都会失效,要重新签署。

[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# ./build-ca
Generating a 1024 bit RSA private key
..............................................................................................++++++
..........++++++
writing new private key to 'ca.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [CN]:
State or Province Name (full name) [BJ]:
Locality Name (eg, city) [BJ]:
Organization Name (eg, company) [esojourn.org]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:
Email Address [[email]pcman@esojourn.org[/email]]:
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]#


生成server端key和crt文件。注意,其中Common Name项目必须填写,其余项目可直接按回车使用环境变量预先设置的默认值。

[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# ./build-key-server server
Generating a 1024 bit RSA private key
............++++++
..........++++++
writing new private key to 'server.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [CN]:
State or Province Name (full name) [BJ]:
Locality Name (eg, city) [BJ]:
Organization Name (eg, company) [esojourn.org]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:openvpn.esojourn.org
Email Address [[email]pcman@esojourn.org[/email]]:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /usr/share/doc/openvpn-2.2.2/easy-rsa/openssl.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName :PRINTABLE:'CN'
stateOrProvinceName :PRINTABLE:'BJ'
localityName :PRINTABLE:'BJ'
organizationName :PRINTABLE:'esojourn.org'
commonName :PRINTABLE:'openvpn.esojourn.org'
emailAddress :IA5STRING:'[email]pcman@esojourn.org[/email]'
Certificate is to be certified until Jul 13 16:17:39 2017 GMT (3650 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]#


证书生成完毕。生成dh文件。
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# ./build-dh
Generating DH parameters, 1024 bit long safe prime, generator 2
This is going to take a long time
..............................+........................................................................................................+.......................................................+.........................................................


现在将刚才生成的证书和配置文件复制到相应目录下。

[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# cp keys/ca.crt /etc/openvpn/
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# cp keys/server.crt /etc/openvpn/
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# cp keys/server.key /etc/openvpn/
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# cp keys/dh1024.pem /etc/openvpn/
sysctl -p


4. 创建新的客户端
openvpn服务器配置好之后,新的客户端还不能立刻连接进来,需要为客户端分别创建属于自己的ssl证书方可。创建的方式如下:
进入openvpn的对应安装目录。生成证书文件。注意,在提示输入CommonName的时候,必须输入唯一一个用户名名字或者域名,以和其他的用户证书相区别。
cd /usr/share/doc/openvpn-2.2.2/easy-rsa[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]# ./build-key client
Generating a 1024 bit RSA private key
....++++++
.......++++++
writing new private key to 'client.key'
-----
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [CN]:
State or Province Name (full name) [BJ]:
Locality Name (eg, city) [BJ]:
Organization Name (eg, company) [esojourn.org]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:pcman
Email Address [[email]pcman@esojourn.org[/email]]:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:
Using configuration from /usr/share/doc/openvpn-2.2.2/easy-rsa/openssl.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName :PRINTABLE:'CN'
stateOrProvinceName :PRINTABLE:'BJ'
localityName :PRINTABLE:'BJ'
organizationName :PRINTABLE:'esojourn.org'
commonName :PRINTABLE:'pcman'
emailAddress :IA5STRING:'[email]pcman@esojourn.org[/email]'
Certificate is to be certified until Jul 13 17:08:27 2017 GMT (3650 days)
Sign the certificate? [y/n]:y
1 out of 1 certificate requests certified, commit? [y/n]y
Write out database with 1 new entries
Data Base Updated
[root@esojourn.org /usr/share/doc/openvpn-2.2.2/easy-rsa]#


生成完毕。在keys目录下即可找到client.key和client.crt。

下面再来看看客户端
5. 客户端的下载安装
官网下载 http://openvpn.net/index.php/download.html
Windows Installer v2.2.2:http://swupdate.openvpn.org/community/releases/openvpn-2.2.2-install.exe

安装时所有组件全装。安装时会装上一个虚拟网卡,系统可能会提示不兼容,不安全什么的。不用管,继续确定安装即可。

6. 初始化
OpenVPN的数据传输过程是基于OpenSSL安全加密的,通信的双方:VPN服务器端、VPN客户端都需要IP安全证书,否则无法建立连接。IP证书也是建立连接的必须条件,基于OpenVPN的VPN建立是没有传统密码验证的。下边配置证书。

首先获得证书。把刚才升成的客户端证书拷过来。3个文件! ca.crt, client.crt, client.key。
另外新建一个esojourn.org.ovpn的文件,用于客户端配置。包含证书文件名、地址等相应参数。ca.crt是全局的CA证书,而client.crt和client.key则是颁发给每个人的个人证书。每个人的个人证书文件不一样,而另外两个文件则一样。

ovpn文件如下,其他ca ca.crt,cert client.crt,key client.key,根据自己的文件名改。

##############################################
# 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 tap
dev 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 tcp
# proto udp

# The hostname/IP and port of the server.
# You can have multiple remote entries
# to load balance between the servers.
remote www.esojourn.org 1194
;remote my-server-2 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-key
persist-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.crt
cert client.crt
key client.key

# Verify server certificate by checking
# that the certicate has the nsCertType
# field set to "server".  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 nsCertType
# field set to "server".  The build-key-server
# script in the easy-rsa folder will do this.
ns-cert-type 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.
;cipher x

# 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

# Silence repeating messages
;mute 20



将这几个文件全部复制到OpenVPN的安装目录下的“config”目录中。如:C:\Program Files\OpenVPN\config

配置完成。


最后编辑: Sonic 编辑于2012/06/29 18:17
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