Nếu bạn lần đầu cấu hình OpenVPN thì rất phức tạp...

chưa kể OpenVPN đã ra đời rất nhiều phiên bản nên khi xem tài liệu trên mạng thì chưa chắc đúng với phiên bản bạn đang cài.

dưới đây là hướng dẫn cài đặt tương ứng với phiên bản openvpn-install-2.3.4-I001-x86_64

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Bước 1 : mở port firewall và router

firewall TCP 1194, UDP 1194

mở ICMPv4

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Bước 2 : chỉnh sửa file vars.bat.sample

set HOME=C:\Program Files\OpenVPN\easy-rsa

set KEY_CONFIG=openssl-1.0.0.cnf

set KEY_DIR=keys

set DH_KEY_SIZE=1024

set KEY_SIZE=1024

set KEY_COUNTRY=VN

set KEY_PROVINCE=HO CHI MINH

set KEY_CITY=HO CHI MINH

set KEY_ORG=CSI

set KEY_EMAIL=nguyentruongthienluong@gmail.com

set KEY_CN=SERVER_CLIENT0x

set KEY_NAME=SCADA

set KEY_OU=ADMIN

set PKCS11_MODULE_PATH=changeme

set PKCS11_PIN=1234

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A challenge password []:12345678

An optional company name []:CSI

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Bước 3 : CMD chạy quyền  admin

cd C:\Program Files\OpenVPN\easy-rsa

init-config.bat

vars.bat

clean-all.bat

build-ca.bat 

=> làm theo từng bước tạo CA

build-key-server.bat server

=> làm theo từng bước tạo cert và key cho server, chữ server trong dòng trên là tên file

build-key.bat client01

=> làm theo từng bước tạo sert và key cho client. chữ client01 trong dòng trên là tên file

build-key.bat client02

=> làm theo từng bước tạo sert và key cho client. chữ client02 trong dòng trên là tên file

build-dh.bat

=> tạo file mã hóa dh 1024

openvpn --genkey --secret keys/ta.key

=> tạo file mã hóa ta.key

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Bước 4 : cấu hình file config cho server

#################################################

# 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 192.168.254.45

# 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 192.168.10.0 255.255.255.0"

;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"

# 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

# 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

route-delay 5

route-method exe

tls-server

tun-mtu 1500

tun-mtu-extra 32

mssfix 1450

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Bước 5 : chạy OpenVPNService trong service (bước này có thể không cần)

hoặc chạy CMD chạy các dòng lệnh sau

net stop OpenVPNService

net start OpenVPNService

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Bước 6 : run vpn trên Server

=> kiểm tra openvpn service đã chạy

=> import file

=> nếu có lỗi gì xem file nhật kí log

=> vào edit config để chỉnh cấu hình

=> chỉnh sửa trực tiếp file open_3600.ovpn sẽ không có tác dụng, v2.4.6

=> ở những lần chạy sau có khả năng lỗi! 

   thì vào stop openvpn service và không start lại

   sau đó thử connect lại vpn

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Bước 7 : copy các file qua máy client

ca.crt

client01.crt

client01.key

ta.key

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Bước 8 : copy file sample config client trong thư mục sample config

qua thư mục config, đổi tên file config ví dụ client_3600.ovpn

(nhớ vào my computer, option, bật tính năng xem đuôi file)

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Bước 9 : chỉnh sửa file cấu hình client

##############################################

# 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 14.224.169.11 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 client01.crt

key client01.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 BF-CBC        # Blowfish (default)

# 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

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Bước 10 : nếu cả 2 máy server và client đã hiện connect vpn,

đã nhận được IP mà không ping thấy nhau,

thì nguyên nhân do openvpn là trên nền linux nên bị firewall windows chặn

dù ping giữa server và client thấy nhau khi cùng chung mạng lan nội bộ

nhưng khi kết nối open vpn thì sẽ không ping được

firewall - inbound rule - new rule - custom - all program - protocol type - 

ICMPv4 - any IP adress - allow the connection - domian, private, public - đặt tên và Finish

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Các điểm lưu ý của file config

trên server và client phải giống nhau

- dev tun

- proto tcp hoặc proto udp

- comp-lzo

- cipher AES-256-CBC

- "C:\\Program Files\\OpenVPN\\easy-rsa\\keys\\..." - sử dụng đường dẫn chính xác, dấu "\" phải là "\\"

các điểm khác giữa server và client

tls-auth "C:\\Program Files\\OpenVPN\\easy-rsa\\keys\\ta.key" 0 - trên server = 0

tls-auth "C:\\Program Files\\OpenVPN\\config\\ta.key" 1 - trên client = 1

remote x.x.x.x 1194 - x.x.x.x là IP tĩnh của server hoặc DDNS mà client truy cập kết nối tới

server x.x.x.x 255.255.255.0 - x.x.x.x dãy IP mà server sẽ cấp phát

local x.x.x.x - x.x.x.x là IP local của server

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Filename Needed By Purpose Secret

ca.crt server + all clients Root CA certificate NO

ca.key key signing machine only Root CA key YES

dh{n}.pem server only Diffie Hellman parameters NO

server.crt server only Server Certificate NO

server.key server only Server Key YES

client1.crt client1 only Client1 Certificate NO

client1.key client1 only Client1 Key YES

client2.crt client2 only Client2 Certificate NO

client2.key client2 only Client2 Key YES

client3.crt client3 only Client3 Certificate NO

client3.key client3 only Client3 Key YES

server cần 6 file

ca.crt

ca.key

dh{n}.pem

server.crt

server.key

ta.key

client cần 3 file

ca.crt

client01.crt

client01.key

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Chúc các bạn may mắn thành công ^.^ !!!