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OpenVPN Project - maaf panjang

1. download dan instalasi
2. konfigurasi
3. runing dan testing

1. download dan instalasi

a. linux ubuntu
dengan level user root, gunakan perintah
apt-get install openvpn
setelah proses selesai konfigurasi openvpn akan berada di /usr/share/doc/openvpn/examples.
agar file konfigurasi asli tidak rusak atau berubah saat kita lakukan konfigurasi, pindahkan folder examples ke /etc/openvpn, yang otomatis terbuat saat downloading dan instalasi pada apt-get install.

b. win32
download file instalasi openvpn windows di http://openvpn.net/download.html.
akan berupa openvpn-2.0.9-install.exe.
jalankan installer dan ikuti saja petunjuk yang ada, atau mudahnya klik saja next hingga selesai.
pada windows akan terbuat shortcut pada start menu yang berisi software openvpn.

2. konfigurasi
pada tahap ini, akan dilakukan konfigurasi pada linux terlebih dahulu, karena openvpn tergolong cross platforn software, sehingga bisa dioperasikan pada linux dan windows, maka tidak akan sulit, hanya akan ada penyesuaian pada masing masing platform.

a. linux ubuntu
setelah mengkopi folder examples tadi, masuk kefolder tersebut /etc/openvpn/examples. akan ada3 buah folder lagi yaitu easy-rsa, sample-config-file, sample-keys.
file file konfigurasi yang dibutuhkan berada pada folder easy-rsa/2.0/. folder ini akan berisi :
build-ca build-key-pass build-req-pass list-crl pkitool vars
build-dh build-key-pkcs12 clean-all Makefile README.gz whichopensslcnf
build-inter build-key-server inherit-inter openssl-0.9.6.cnf.gz revoke-full
build-key build-req keys openssl.cnf sign-req
file konfigurasi dasar adalah vars, dimana berisi informasi penting openvpn yang akan di buat, dalam hal ini openvpn akan di konfigurasi menggunakan easy-rsa :

# easy-rsa parameter settings

# NOTE: If you installed from an RPM,
# don't edit this file in place in
# /usr/share/openvpn/easy-rsa --
# instead, you should copy the whole
# easy-rsa directory to another location
# (such as /etc/openvpn) so that your
# edits will not be wiped out by a future
# OpenVPN package upgrade.

# This variable should point to
# the top level of the easy-rsa
# tree.
export D=`pwd`

# This variable should point to
# the openssl.cnf file included
# with easy-rsa.
export KEY_CONFIG=$D/openssl.cnf

# Edit this variable to point to
# your soon-to-be-created key
# directory.
#
# WARNING: clean-all will do
# a rm -rf on this directory
# so make sure you define
# it correctly!
export KEY_DIR=$D/keys

# Issue rm -rf warning
echo NOTE: when you run ./clean-all, I will be doing a rm -rf on $KEY_DIR

# Increase this to 2048 if you
# are paranoid. This will slow
# down TLS negotiation performance
# as well as the one-time DH parms
# generation process.
export KEY_SIZE=1024

# These are the default values for fields
# which will be placed in the certificate.
# Don't leave any of these fields blank.
export KEY_COUNTRY=KG
export KEY_PROVINCE=NA
export KEY_CITY=BISHKEK
export KEY_ORG="OpenVPN-TEST"
export KEY_EMAIL="me@myhost.mydomain"

konfigurasi yang dibutuhkan hanya pada baris export KEY_SIZE=1024 dan 5 baris terakhir.
jika ingin openvpn lebih secure dan lebih lambat ubah export KEY_SIZE=1024 menjadi 2048, (if you are paranoid). ubah 5 baris terakhir sesuai kebutuhan.
ubah dengan perintah
vi vars atau vim vars atau menggunakan editor lain
jika sudah jalankan file vars tersebut
. ./vars
./clean-all
perintah clean-all akan menghapus semua konfigurasi lama yang pernah dibuat pada folder keys
./build-ca
perintah build-ca untuk membuat sertifikat openvpn yang baru pada folder keys, akan muncul sekuen :

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) [KG]:
State or Province Name (full name) [NA]:
Locality Name (eg, city) [BISHKEK]:
Organization Name (eg, company) [OpenVPN-TEST]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:OpenVPN-CA
Email Address [me@myhost.mydomain]:

semua informasi pada [ ] adalah informasi yang ada pada vars yang sudah di edit tadi, tekan enter saja untuk pengisian default (sama dengan isi [ ]), kecuali seksi
common name
harus diisi manual sesuai dengan nama yang akan kita berikan pada sertifikat CA openvpn, kalau tidak proses akan gagal.
akan ada file sertifikat openvpn (ca) pada folder keys
setelah itu akan dibuat keyt untuk server openvpn, dengan menggunakan perintah
./build-key-server server
perintah ini akan membuat key openvpn-server bernama server, dengan menggunakan nama "server" akan berfungsi untuk autentikasi lebih lanjut.

Generating a 1024 bit RSA private key
......++++++
...++++++
writing new private key to 'VPN-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) [DE]:
State or Province Name (full name) [BY]:
Locality Name (eg, city) [Regensburg]:
Organization Name (eg, company) [Feilner-IT]:
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:server
Email Address [security@feilner-it.net]:
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/examples/easy-rsa/openssl.cnf
Check that the request matches the signature
Signature ok
The Subject's Distinguished Name is as follows
countryName :PRINTABLE:'DE'
stateOrProvinceName :PRINTABLE:'BY'
localityName :PRINTABLE:'Regensburg'
organizationName :PRINTABLE:'Feilner-IT'
commonName :PRINTABLE:'server'
emailAddress :IA5STRING:'security@feilner-it.net'
Certificate is to be certified until Nov 17 23:40:04 2015 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

pada seksi 'A challenge password' dan 'An optional company name' bisa dikosongkan, dan yang penting adalah 2 pernyataan terakhir harus berisi argumen positif atau 'y'.
setelah tahap ini selesai maka akan ada file sertifikat server pada folder keys
ls -l keys

-rw-r--r-- 1 root root 3653 2005-11-20 00:40 01.pem
-rw-r--r-- 1 root root 1233 2005-11-20 00:39 ca.crt
-rw------- 1 root root 887 2005-11-20 00:39 ca.key
-rw-r--r-- 1 root root 104 2005-11-20 00:40 index.txt
-rw-r--r-- 1 root root 21 2005-11-20 00:40 index.txt.attr
-rw-r--r-- 1 root root 0 2005-11-20 00:31 index.txt.old
-rw-r--r-- 1 root root 3 2005-11-20 00:40 serial
-rw-r--r-- 1 root root 3 2005-11-20 00:31 serial.old
-rw-r--r-- 1 root root 3653 2005-11-20 00:40 server.crt
-rw-r--r-- 1 root root 688 2005-11-20 00:40 server.csr
-rw------- 1 root root 887 2005-11-20 00:40 server.key

setelah membuat sertifikat server, kemudian membuat sertifikat untuk client, dengan menggunakan perintah
./build-key client
proses pembuatan akan sama dengan saat membuat key server, bagian yang terpenting adalah pada Common Name, harus diisi manual, dan jika akan membuat client key lebih dari 1 Common Name masing-masing client harus berbeda.
setelah selesai kemudian membuat Diffie Hellman parameters dengan menggunakan perintah
./build-dh

Generating DH parameters, 1024 bit long safe prime, generator 2
This is going to take a long time
.................+...........................................
...................+.............+.................+.........
......................................

lama proses tergantung pada isi variabel export KEY_SIZE pada vars, semakin besar isinya (2048) semakin lama prosesnya.
jika sudah selesai maka konfigurasi dasar sertifikat dan key pada openvpn manggunakan metode easy-rsa selesai.semua file yang dibutuhkan akan ditampung pada folder keys.
berikut adalah contoh tabel distribusi file sertifikat dan keys

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

dengan ini administrator dapat menentukan hak akses pada setiap file tersebut. kemudian agar lebih cantik copy folder keys tadi ke /etc/openvpn
gunakan perintah
openvpn --genkey --secret ta.key
untuk membuat authentication key server, yang digunakan sebagai tambahan kunci koneksi antara server dan client openvpn. gunakan perintah saat berada di /etc/openvpn (menjadi satu dengan server.conf).
semua file diatas hanya sekedar dasar dan kebutuhan untuk openvpn saja, harus dibuat konfigurasi sendiri untuk server dan client.

MEMBUAT KONFIGURASI SERVER DAN CLIENT
untuk lebih mudahnya copy file server.conf dari folder examples/sample-config-files ke folder /etc/openvpn, jika masih dalam bentuk .gz dekompres dulu dengan
gzip -d server.conf.gz
buka server.conf dengan editor

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

# 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
# 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"

# 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

edit isi file ini sesuai kebutuhan.
sama halnya dengan file konfigurasi untuk client, supaya terorganisir terlebih dahulu buat folder 'configs' pada /etc/openvpn, untuk menyimpan semua file key untuk client. setelah itu copy client.conf dari sample-config-file ke folder 'configs' yang di buat tadi. buka dengan editor

##############################################
# 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 my-server-1 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

edit sesuai kebutuhan.
copy semua file dan key yang dibutuhkan client dari folder keys ke folder configs. kemudian distribusikan configs tersebut ke client yang akan menggunakan openvpn.

b. win32

karena server side adalah linux dan win32 berperan sebagai client, jadi hanya copy saja folder 'configs' tadi ke windows dengan menggunakan winscp atau dengan cara lain.

3. runing dan testing

a. linux ubuntu

SERVER SIDE
untuk menjalankan openvpn dengan menggunakan konfigurasi yang sudah kita buat, masuk ke direktori tempat file konfigurasi berada (server.conf) contoh
cd /etc/openvpn
kemudian gunakan perintah
openvpn server.conf &
jika pada log sudah tidak terdapat error dan proses ini (starting up tunnel) berhasil, maka akan ada network interface virtual baru yang akan dibuat. cek dengan
ifconfig
akan terbentuk interface tun/tap yang baru. dapat dilakukan pengetesan dengan melakukan ping ke interface openvpn tersebut.

CLIENT SIDE
sama dengan server side masuk ke direktori dimana file client.conf disimpan, contoh
cd /etc/openvpn/configs
jalankan client dengan perintah
openvpn client.conf
jika starting up tunnel berhasil maka akan terbentuk interface virtual baru. server dan client tidak akan bisa dijalankan pada mesin yang sama.

eth0 Link encap:Ethernet HWaddr 00:15:58:B9:76:7B
inet addr:192.168.42.135 Bcast:192.168.42.255 Mask:255.255.255.0
inet6 addr: fe80::215:58ff:feb9:767b/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:530309 errors:0 dropped:0 overruns:0 frame:0
TX packets:612908 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:90556737 (86.3 MiB) TX bytes:1102905696 (1.0 GiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:31007 errors:0 dropped:0 overruns:0 frame:0
TX packets:31007 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:56798907 (54.1 MiB) TX bytes:56798907 (54.1 MiB)

peth0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:530310 errors:0 dropped:0 overruns:0 frame:0
TX packets:985986 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:93884697 (89.5 MiB) TX bytes:1130585418 (1.0 GiB)
Interrupt:18

tun0 Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00 <<===
inet addr:10.8.0.1 P-t-P:10.8.0.2 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:100
RX bytes:0 (0.0 b) TX bytes:0 (0.0 b)

vif0.0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::fcff:ffff:feff:ffff/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:612908 errors:0 dropped:0 overruns:0 frame:0
TX packets:530309 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1102905696 (1.0 GiB) TX bytes:90556737 (86.3 MiB)

xenbr0 Link encap:Ethernet HWaddr FE:FF:FF:FF:FF:FF
inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING NOARP MTU:1500 Metric:1
RX packets:93321 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:12021345 (11.4 MiB) TX bytes:0 (0.0 b)

b. win32

membuat virtual network interface dahulu, dengan cara start-->all programs-->openvpn-->Add a new TAP-Win32 virtual ethernet adapter. maka pada 'network connection' akan ada adapter virtual baru.
sebelum menggunakan file konfigurasi tadi, karena dikonfigurasi di linux, maka agar konfigurasi openvpn yang sudah dibuat bisa berjalan di windows, ubah dulu ekstensi .conf menjadi .ovpn setelah itu klik kanan pada file .ovpn dan pilih 'start openvpn on this config file'

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : sskom.co.id
IP Address. . . . . . . . . . . . : 192.168.42.243
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.42.251

Ethernet adapter MyTap: <<===

Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 10.8.0.6
Subnet Mask . . . . . . . . . . . : 255.255.255.252
Default Gateway . . . . . . . . . :

jangan tutup setiap jendela konsole atau command prompt dimana proses openvpn dijalankan. karena openvpn akan langsung mati juga.

Psutaka : openvpn.net