安装配置如下：
系统已经安装了
openssl097a-0.9.7a-9.el5_4.2
openssl-0.9.8e-12.el5_4.6
openssl-perl-0.9.8e-12.el5_4.6
openssl-devel-0.9.8e-12.el5_4.6
1、下载所需要的包；
wget
wget
2、rpm安装很简单，此处省略；
3、cp /usr/share/doc/openvpn-2.0.9/easy-rsa /etc/openvpn
4、修改相关文件执行权限，为了方便我一次把要使用的文件都加了可执行权限；
[root@vpn easy-rsa]#cd /etc/openvpn/easy-rsa
[root@vpn easy-rsa]#chmod a+x build-ca build-dh build-key build-key-server clear-all vars
5、修改vars文件，把一些变量加入到系统里，为了操作方便，我把原来的全都注释了，然后添加如下变量；
export D=`pwd`
export KEY_DIR=$D/keys
export KEY_CONFIG=$D/openssl.cnf
export KEY_SIZE=1024
export KEY_COUNTRY=CN
export KEY_PROVINCE=BJ
export KEY_CITY=BJ
export KEY_ORG="Open×××-TEST"
export KEY_EMAIL=""
可以根据具体情况加以更改，修改完成后可以直接执行就行了；
6、初始化Keys目录，创建所需要的文件和目录；
[root@vpn easy-rsa]# ./clean-all;
7、生成 Root CA证书，主要可以用在以后为Server和Client签发相关证书；
[root@vpn 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) [Open×××-TEST]:
Organizational Unit Name (eg, section) []:IT
Common Name (eg, your name or your server's hostname) []:Openvpn
Email Address [test@domain.comt]:
8、为Server签发相应证书；
[root@vpn 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) [Open×××-TEST]:
Organizational Unit Name (eg, section) []:IT
Common Name (eg, your name or your server's hostname) []:Server
Email Address [test@domain.comt]:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:12348765
An optional company name []:Center
Using configuration from /etc/openvpn/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:'Open×××-TEST'
organizationalUnitName:PRINTABLE:'IT'
commonName :PRINTABLE:'Server'
emailAddress :IA5STRING:'test@domain.comt'
Certificate is to be certified until Oct 19 11:14:20 2020 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
9、为客户端生成相应的证书，网上资料说一个证书只能用在第一个拨上的客户使用，我使用一个证书分别在两台机器上，没发现类似问题。
[root@vpn 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) [Open×××-TEST]:
Organizational Unit Name (eg, section) []:IT
Common Name (eg, your name or your server's hostname) []:client
Email Address [test@domain.comt]:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:12348765
An optional company name []:Center
Using configuration from /etc/openvpn/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:'Open×××-TEST'
organizationalUnitName:PRINTABLE:'IT'
commonName :PRINTABLE:'client'
emailAddress :IA5STRING:'test@domain.comt'
Certificate is to be certified until Oct 19 11:16:14 2020 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
10、生成Diffie-Hellman文件；
[root@vpn easy-rsa]# ./build-dh
Generating DH parameters, 1024 bit long safe prime, generator 2
This is going to take a long time
................................+...+.+..................+..........+.............................
+.............................................................................................................................
+..................................................................................................+..............................................
.+................+.......................................................................................................
...................................................................+.. ................................................................
.+................................+...f...................................a...............+........+.............................................
.............................+...+.....................................................................................................................
...............................................................................+..+.............................................+..................................
......................................................................................................................................................................
..+................................................+.................................+...................................................................................
................................................................................+........................................................+.............................
...............................................................+........................+.............................................................................
..........+..+....................+........................................+...................+............................................................+....+..
.....................................................+.........+.+..........................................+...................................................
..................+.............+.........................................................................+.......................................................
..............................................+...............................................+....+..............+...........................................
+......................................+...............................................................+.................................................
..+.................................................+..........................................+...+..........................................................
................++*++*++*
11、看网上说为防止恶意攻击生成个"HMAC firewall",不知道是真是假，反正我也生成了一个；
[root@vpn openvpn]#openvpn --genkey --secret keys/ta.key
在keys下自动生成了个ta.key,留着以后备用的；
12、将生成的CA证书及密钥拷贝到/etc/openvpn下，除此之外还有服务器的配置文件；
[root@vpn openvpn]# ll
-rw-r--r-- 1 root root 1261 Oct 22 15:39 ca.crt
-rw------- 1 root root 887 Oct 22 15:39 ca.key
-rw-r--r-- 1 root root 245 Oct 22 15:39 dh1024.pem
drwxr-xr-x 5 root root 4096 Nov 8 18:53 easy-rsa
-rw------- 1 root root 0 Nov 8 20:02 ipp.txt
-rw-r--r-- 1 root root 10305 Nov 8 15:15 server.conf
-rw-r--r-- 1 root root 3696 Oct 22 15:39 server.crt
-rw------- 1 root root 887 Oct 22 15:39 server.key
-rw------- 1 root root 636 Nov 4 20:56 ta.key
13、修改server.conf,我把修改好的直接拿过来了；
[root@vpn openvpn]# cat server.conf.old
#################################################
# Sample Open××× 2.0 config file for #
# multi-client server. #
# #
# This file is for the server side #
# of a many-clients <-> one-server #
# Open××× configuration. #
# #
# Open××× 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\\Open×××\\config\\foo.key" #
# #
# Comments are preceded with '#' or ';' #
#################################################
# Which local IP address should Open×××
# listen on? (optional)
;local a.b.c.d
# Which TCP/UDP port should Open××× listen on?
# If you want to run multiple Open××× 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 ×××, 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 ××× 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.
# Open××× 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 ××× subnet
# for Open××× 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
server 192.168.168.0 255.255.255.0
# Maintain a record of client <-> virtual IP address
# associations in this file. If Open××× 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
# 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 Open××× client
# address pool (10.8.0.0/255.255.255.0)
# back to the Open××× server.
;push "route 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"
;push "route 192.168.7.0 255.255.255.0"
push "route 192.168.168.0 255.255.255.0"
push "route 192.168.0.0 255.255.255.0"
# To assign specific IP addresses to specific
# clients or if a connecting client has a private
# subnet behind it that should also have ××× 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 ×××. 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 ××× 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 Open××× 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 ×××, causing
# all IP traffic such as web browsing and
# and DNS lookups to go through the ×××
# (The Open××× server machine may need to NAT
# the TUN/TAP interface to the internet in
# order for this to work properly).
# CAVEAT: May break client's network config if
# client's local DHCP server packets get routed
# through the tunnel. Solution: make sure
# client's local DHCP server is reachable via
# a more specific route than the default route
# of 0.0.0.0/0.0.0.0.
;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
;push "dhcp-option DNS 10.8.0.1"
;push "dhcp-option WINS 10.8.0.1"
push "dhcp-option DNS 192.168.0.100"
# 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
;tls-auth ta.key 0
# 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 ××× 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 Open×××
# 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 /var/log/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\Open×××\log" directory).
# Use log or log-append to override this default.
# "log" will truncate the log file on Open××× startup,
# while "log-append" will append to it. Use one
# or the other (but not both).
log /var/log/openvpn.log
log-append /var/log/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
14、启动openvpn；
[root@vpn openvpn]#service openvpn start
15、打开转发功能；
[root@vpn openvpn]# echo "1" > /proc/sys/net/ipv4/ip_forward
16、为了能让客户端访问服务器端的内网还应该加一条规则才能正常访问，否则只能ping通网关，访问不到内网。
[root@vpn openvpn]#iptables -t nat -A POSTROUTING -s 192.168.168.0/24 -o eth1 -j SNAT --to-source 192.168.0.151
到此，服务器端的配置已经完成，但此时不能支持客户端的Ldap认证，如果需要客户端连接×××时支持ldap验证，需要在服务器端添加如下配置；
1、安装openvpn-auth-ldap-2.0.3-3.el5,下载路径访问，直接去rpmfind查找就行了；
2、安装完成后在/etc/openvpn下多出一个auth文件夹，下面多出一个ldap.conf文件；
3、修改server.conf,添加如下三行配置；
tls-auth ta.key 0
cipher AES-128-CBC # AES
plugin /usr/lib/openvpn/plugin/lib/openvpn-auth-ldap.so "/etc/openvpn/auth/ldap.conf"
4、修改ldap.conf;
[root@vpn auth]# cat ldap.conf
<LDAP>
# LDAP server URL
URL
# Bind DN (If your LDAP server doesn't support anonymous binds)
# BindDN uid=Manager,ou=People,dc=example,dc=com
BindDN "CN=test,CN=Users,DC=domain,DC=com"
# Bind Password
# Password SecretPassword
Password abc
# Network timeout (in seconds)
Timeout 60
# Enable Start TLS
TLSEnable no
# Follow LDAP Referrals (anonymously)
FollowReferrals no
# TLS CA Certificate File
TLSCACertFile /usr/local/etc/ssl/ca.pem
# TLS CA Certificate Directory
TLSCACertDir /etc/ssl/certs
# Client Certificate and key
# If TLS client authentication is required
TLSCertFile /usr/local/etc/ssl/client-cert.pem
TLSKeyFile /usr/local/etc/ssl/client-key.pem
# Cipher Suite
# The defaults are usually fine here
# TLSCipherSuite ALL:!ADH:@STRENGTH
</LDAP>
<Authorization>
# Base DN
BaseDN "DC=domain,DC=com"
# User Search Filter
#SearchFilter "(sAMAccountName=%u)"
#SearchFilter "(&(uid=%u)(accountStatus=active))"
SearchFilter "(&(sAMAccountName=%u)(msNPAllowDialin=TRUE))"
# Require Group Membership
RequireGroup false
# Add non-group members to a PF table (disabled)
#PFTable ips_vpn_users
#<Group>
# SearchFilter "(&(sAMAccountName=%u)(msNPAllowDialin=TRUE))"
# MemberAttribute uniqueMember
# Add group members to a PF table (disabled)
#PFTable ips_vpn_eng
#</Group>
</Authorization>
5、OK，此时服务器已经支持了ldap认证。
6、客户端的配置文件如下所示；
##############################################
# Sample client-side Open××× 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 ××× 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 my-server-1 1194
;remote my-server-2 1194
remote X.X.X.X 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 Open××× 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 Open×××
# 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 "C:\\Program Files\\Open×××\\config\\ca.crt"
cert "C:\\Program Files\\Open×××\\config\\client.crt"
key "C:\\Program Files\\Open×××\\config\\client.key"
tls-auth "C:\\Program Files\\Open×××\\config\\ta.key" 1
auth-user-pass
# 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
cipher AES-128-CBC
# Enable compression on the ××× 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
7、如果服务器端不支持ldap将上面的配置中如下认证去掉就行了；
tls-auth "C:\\Program Files\\Open×××\\config\\ta.key" 1
auth-user-pass
cipher AES-128-CBC
注意：X.X.X.X代表×××的对外IP，如果客户端是非Win时，上面的路径写法不所不同，都是大同小异的。
[root@vpn openvpn]# service openvpn start
Starting openvpn: /usr/sbin/openvpn: error while loading shared libraries: libssl.so.4: cannot open shared object file: No such file or directory
[FAILED]
请检查对应的openssl是否安装；
openssl097a-0.9.7a-9.el5_2.1.i386.rpm
openssl-0.9.8e-12.el5.i386.rpm
openssl-0.9.8e-12.el5.i686.rpm
openssl-devel-0.9.8e-12.el5.i386.rpm
openssl-perl-0.9.8e-12.el5.i386.rpm
http://hi.baidu.com/adriannet/blog/item/ebc4280708fed1dd7a894760.html
