Centos OpenVPN 簡易建置流程

Centos OpenVPN 簡易建置流程


Setp 1
載 RPMforge 套件並安裝 http://rpmrepo.org/RPMforge/Using

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.1-1.el5.rf.i386.rpm
rpm -Uvh rpmforge-release-0.5.1-1.el5.rf.i386.rpm


Setp 2
安裝OpenVPN

yum install openvpn


Setp 3
憑證製作

mkdir /etc/openvpn/easy-rsa/
cp -Rf /usr/share/doc/openvpn-2.2.2/easy-rsa/* /etc/openvpn/easy-rsa/
cd /etc/openvpn/easy-rsa/2.0
chmod a+x build* clean-all inherit-inter list-crl pkitool revoke-full sign-req whichopensslcnf


Step 4
編輯vars檔案

vi vars
#key的長度，2048安全性更高一些
export KEY_SIZE=1024(2048)

#Server root CA有效期限（天數）
export CA_EXPIRE=730

#client憑證有效期限 (天數)
export KEY_EXPIRE=365

#以下部份是憑證資料
export KEY_COUNTRY="TW"
export KEY_PROVINCE="Taiwan"
export KEY_CITY="Taipei"

#以下兩個可自行設定
export KEY_ORG="Fort-Funston"
export KEY_EMAIL="me@myhost.mydomain"



Setp 5
製作Server端憑證

source ./vars
./clean-all
產生檔案：dh1024.pem (export KEY_SIZE=1024)

./build-dh
#產生檔案：ca.crt ca.key

./build-ca
產生檔案：server.csr server.key

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) [TW]:En
 State or Province Name (full name) [Taiwan]:En
 Locality Name (eg, city) [Taipei]:En
 Organization Name (eg, company) [Black-Xstar Net Empire]:En
 Organizational Unit Name (eg, section) []:En
 Common Name (eg, your name or your server’s hostname) [Black-Xstar Net Empire CA]:En
 Name []:En
 Email Address [webmaster@black-xstar.com]:En


# Server端金鑰
./build-key-server server (server 自訂)

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) [TW]:En
 State or Province Name (full name) [Taiwan]:En
 Locality Name (eg, city) [Taipei]:En
 Organization Name (eg, company) [Black-Xstar Net Empire]:En
 Organizational Unit Name (eg, section) []:En
 Common Name (eg, your name or your server’s hostname) [server]:En
 Name []:En
 Email Address [webmaster@black-xstar.com]:En

Please enter the following ‘extra’ attributes
 to be sent with your certificate request
 A challenge password []:En
 An optional company name []:En
 Using configuration from /etc/openvpn/easy-rsa/2.0/openssl.cnf
 Check that the request matches the signature
 Signature ok
 The Subject’s Distinguished Name is as follows
 countryName           RINTABLE:’CN’
 stateOrProvinceName   RINTABLE:’GD’
 localityName          RINTABLE:’GZ’
 organizationName      RINTABLE:’Black-Xstar Net Empire’
 commonName            RINTABLE:’server’
 emailAddress          :IA5STRING:’webmaster@black-xstar.com’
 Certificate is to be certified until Nov 18 17:25:15 2019 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


# Client端金鑰
./build-key client (client 自訂)

Generating a 1024 bit RSA private key
 …….++++++
 ………++++++
 writing new private key to ‘client1.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]:En
 State or Province Name (full name) [GD]:En
 Locality Name (eg, city) [GZ]:En
 Organization Name (eg, company) [Black-Xstar Net Empire]:En
 Organizational Unit Name (eg, section) []:En
 Common Name (eg, your name or your server’s hostname) [client1]:En
 Name []:En
 Email Address [webmaster@black-xstar.com]:En

Please enter the following ‘extra’ attributes
 to be sent with your certificate request
 A challenge password []:En
 An optional company name []:En
 Using configuration from /etc/openvpn/easy-rsa/2.0/openssl.cnf
 Check that the request matches the signature
 Signature ok
 The Subject’s Distinguished Name is as follows
 countryName           RINTABLE:’CN’
 stateOrProvinceName   RINTABLE:’GD’
 localityName          RINTABLE:’GZ’
 organizationName      RINTABLE:’Black-Xstar Net Empire’
 commonName            RINTABLE:’client1′
 emailAddress          :IA5STRING:’webmaster@black-xstar.com’
 Certificate is to be certified until Nov 18 17:31:21 2019 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


#Step 6
#建立link
cd /etc/openvpn
ln -s easy-rsa/2.0/keys/


Step 7

vi server.conf

********************START************************
# Which local IP address should OpenVPN
# listen on? (optional)
local 203.70.8.61 (更改IP)

# 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 (更改 port)

# TCP or UDP server?
;proto tcp
proto udp (tcp/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 (dh1024.pem) (export KEY_SIZE=1024)

# 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 10.9.0.0 255.255.255.0 (VPN網段)

# 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 (cleint ip 會記錄在 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 192.168.10.0 255.255.255.0"
;push "route 192.168.20.0 255.255.255.0"
push "route 10.10.1.0 255.255.255.0" (routing 10.10.1.* 這個網段)

# 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 /etc/openvpn/ccd (將固定IP寫入 /etc/openvpn/ccd 讓users撥號時取得固定IP)
;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" (不取得VPN的網段的GW)

# 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 208.67.222.222"
;push "dhcp-option DNS 208.67.220.220"

# 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 (讓撥入vpn的users能互相連接)

# 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
********************END***************************

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五、固定IP地址分配

在Server端配置文件(server.conf)里：

;client-config-dir ccd
;route 10.8.0.0 255.255.255.252

在/etc/openvpn文件夾下新建名為ccd文件夾，在ccd 文件夾里以客戶名為名新建文件，內容格式如下：

ifconfig-push 10.8.0.20 10.8.0.120

客戶端啟動後即獲得IP地: 10.8.0.20

要注意上面格式只對linux有效，如果客戶端為windows,則客戶端會連接不成功。因為openvpn在windows下時， 其local IP 與remote IP 必須在網址掩碼
為255.255.255.252的同一網段內，而且不能取頭尾兩端的IP，因此一個openvpn連接在windows下最少要佔用4個ip地址windows 下的客戶端IP配置必須為如下形式

ifconfig-push 10.8.0.30 10.8.0.29

因為10.8.0.28/30網段包含以下IP： 10.8.0.28-31, 去除頭尾，只有29與30可用。其他類推。



六、訪問外網設置

開啟服務器端路由轉發功能
# echo 1 > /proc/sys/net/ipv4/ip_forward

#為了使CentOS重啟後仍然開啟路由轉發功能我們需要再執行下列命令
# sysctl -w net.ipv4.ip_forward=1

添加iptables轉發規則

#因為我的CentOS是ADSL撥號上網,所以把出口設置成ppp0,請根據實際情況設置， 如eth0

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o ppp0 -j MASQUERADE

必須保證server.conf配置中,有下面三個配置

push "dhcp-option DNS 10.8.0.1"
push "dhcp-option DNS 202.103.44.150" #客戶端獲得的DNS地址
push "dhcp-option DNS 202.103.24.68" #客戶端獲得的DNS地址


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cp /etc/openvpn/easy-rsa/2.0/keys/dh1024.pem /etc/openvpn/
cp /etc/openvpn/easy-rsa/2.0/keys/ca.* /etc/openvpn/
cp /etc/openvpn/easy-rsa/2.0/keys/server.* /etc/openvpn/

ll -ls  /etc/openvpn/
-rw-r--r-- 1 root root  1379 May  7 16:21 ca.crt
-rw------- 1 root root   887 May  7 16:21 ca.key
drwxr-xr-x 2 root root  4096 May  8 11:23 ccd
-rw-r--r-- 1 root root   245 May  7 16:21 dh1024.pem
drwxr-xr-x 5 root root  4096 May  7 16:14 easy-rsa
-rw------- 1 root root    76 May  8 12:12 ipp.txt
lrwxrwxrwx 1 root root    18 May  7 16:18 keys -> easy-rsa/2.0/keys/
-rw------- 1 root root   370 May  8 12:12 openvpn-status.log
-rw-r--r-- 1 root root 10366 May  8 11:08 server.conf
-rw-r--r-- 1 root root  4120 May  7 16:22 server.crt
-rw-r--r-- 1 root root   729 May  7 16:22 server.csr
-rw------- 1 root root   887 May  7 16:22 server.key

vim /etc/openvpn/ccd/client

ifconfig-push 10.9.0.65 10.9.0.66 (255.255.255.252)


[ 1, 2] [ 5, 6] [ 9, 10] [ 13, 14] [ 17, 18]
[ 21, 22] [ 25, 26] [ 29, 30] [ 33, 34] [ 37, 38]
[ 41, 42] [ 45, 46] [ 49, 50] [ 53, 54] [ 57, 58]
[ 61, 62] [ 65, 66] [ 69, 70] [ 73, 74] [ 77, 78]
[ 81, 82] [ 85, 86] [ 89, 90] [ 93, 94] [ 97, 98]
[101,102] [105,106] [109,110] [113,114] [117,118]
[121,122] [125,126] [129,130] [133,134] [137,138]
[141,142] [145,146] [149,150] [153,154] [157,158]
[161,162] [165,166] [169,170] [173,174] [177,178]
[181,182] [185,186] [189,190] [193,194] [197,198]
[201,202] [205,206] [209,210] [213,214] [217,218]
[221,222] [225,226] [229,230] [233,234] [237,238]
[241,242] [245,246] [249,250] [253,254]



chkconfig openvpn on
/etc/init.d/openvpn start


Step 8
#允許轉IPv4轉送

vim /etc/init.d/openvpn

echo 1 > /proc/sys/net/ipv4/ip_forward (註解移掉)

or

vi /etc/sysctl.conf

net.ipv4.ip_forward = 0 改成 net.ipv4.ip_forward = 1
sysctl -p


/etc/init.d/openvpn start

How to insatll VPN on Windows Server