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OpenVPN Overview

OpenVPN is an SSL/TLS VPN solution. It is able to traverse NAT connections and firewalls. This page explain briefly how to configure a VPN with OpenVPN, from both server-side and client-side.


Установка openvpn на сервере и клиенте.

# apt-get install openvpn


OpenVPN может использовать аутентификацию по логину/паролю, по ключу, сертификату и т.д.

Тест VPN

Тест соединения.

Тест сервера

В консоли сервера выполняем

# openvpn --dev tun1 --ifconfig

В консоли должно получится примерно следующее:

Wed Mar  7 06:03:03 2012 NOTE: OpenVPN 2.1 requires '--script-security 2' or higher to call user-defined scripts or executables
Wed Mar  7 06:03:03 2012 ******* WARNING *******: all encryption and authentication features disabled -- all data will be tunnelled as cleartext
Wed Mar  7 06:03:03 2012 TUN/TAP device tun1 opened

Проверим что openvpn запущен, проверим конфигурацию сети sudo ifconfig -a. Вывод примерно следующий:

tun1      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:  P-t-P:  Mask:
          RX packets:13 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:2262 (2.2 KiB)  TX bytes:1819 (1.7 KiB)

Обратите внимание, еслы вы "убили" openvpn (например нажали Control-C в консоли), вы не увидите сетевого соединения.

Тест клиента

# openvpn --remote SERVER_IP --dev tun1 --ifconfig
Wed Mar  7 18:05:30 2012 Peer Connection Initiated with [AF_INET]SERVER_IP:PORT
Wed Mar  7 18:05:30 2012 Initialization Sequence Completed

Теперь можем проверить ping.

Static-Key VPN

На сервере, переходим в директорию /etc/openvpn , и выполняем команду для генерации статического ключа:

# openvpn --genkey secret static.key

Скопируйте ключ на клиента в директорию /etc/openvpn , для безопасности используйте scp или sftp.

На сервере, создайте новый /etc/openvpn/tun0.conf файл и добавьте следующее:

dev tun0
secret /etc/openvpn/static.key

Здесь 10.9.8.x ваша VPN подсеть, - IP адрес сервера, - IP клиента.

На клиенте, скопируйте /etc/openvpn/static.key файл с сервера, создайте новый /etc/openvpn/tun0.conf файл и запишите в него следующее:

dev tun0
secret /etc/openvpn/static.key

На FIREWALL необходимо открыть UDP 1194 (порт по умолчанию).

If you are using ?shorewall, on both devices, add a new VPN zone to represent tun0 and create a default policy for it. This means adding something to the following files in /etc/shorewall:

Bear in mind that 90% of all connection problems encountered by new OpenVPN users are firewall-related.

Start OpenVPN by hand on both sides with the following command:

# openvpn --config /etc/openvpn/tun0.conf --verb 6  // verbose output.

You should probably configure your route at this step.

To verify that the VPN is running, you should be able to ping from the server and from the client.

TLS-enabled VPN

In server, copy key generating script from openvpn example to /etc/openvpn and add executable permission:

# cd /etc/openvpn
# mkdir easy-rsa

In Jessie and above easy-rsa is a separate package. So you'll have to install that in addition to openvpn.

On Wheezy:

# cp -R /usr/share/doc/openvpn/examples/easy-rsa/2.0/* easy-rsa/

On Jessie and above:

# apt-get install easy-rsa
# cp -R /usr/share/easy-rsa/* easy-rsa/

Edit /etc/openvpn/easy-rsa/vars bottom according to your organization.

export KEY_CITY="SanFrancisco"
export KEY_ORG="Fort-Funston"
export KEY_EMAIL="mail@domain"
export KEY_EMAIL=mail@domain

Execute the following command:

# cd easy-rsa/
# touch keys/index.txt
# echo 01 > keys/serial
# . ./vars  # set environment variables
# ./clean-all



# ./build-ca

It will generate ca.crt and ca.key in /etc/openvpn/easy-rsa/keys/ directory.


# ./build-key-server server

It will generate server.crt and server.key in /etc/openvpn/easy-rsa/keys/, and signed with your root certificate.

Generate BUILD DIFFIE-HELLMAN PARAMETERS (necessary for the server end of a SSL/TLS connection):


Generate key for each client:

./build-key clientname

Generate key with password (this protect the key and request the password every time that you connect to the server), for each client:

./build-key-pass clientname

It will generate keys in /etc/openvpn/easy-rsa/keys/

Copy the ca.crt, clientname.crt, clientname.key from Server to Client /etc/openvpn/easy-rsa/keys/ directory.

Check OpenVPN RSA Key and VPN for details.

Test the connectivity from command line.


openvpn --dev tun1 --ifconfig --tls-server --dh /etc/openvpn/easy-rsa/keys/dh1024.pem --ca /etc/openvpn/easy-rsa/keys/ca.crt --cert /etc/openvpn/easy-rsa/keys/server.crt --key /etc/openvpn/easy-rsa/keys/server.key --reneg-sec 60 --verb 5


openvpn --remote SERVER_IP --dev tun1 --ifconfig --tls-client --ca /etc/openvpn/easy-rsa/keys/ca.crt --cert /etc/openvpn/easy-rsa/keys/clientname.crt --key /etc/openvpn/easy-rsa/keys/clientname.key --reneg-sec 60 --verb 5

If the connection is successful create file configuration.

In Server create /etc/openvpn/server.conf as follows:

port 1194
proto udp
dev tun

ca      /etc/openvpn/easy-rsa/keys/ca.crt    # generated keys
cert    /etc/openvpn/easy-rsa/keys/server.crt
key     /etc/openvpn/easy-rsa/keys/server.key  # keep secret
dh      /etc/openvpn/easy-rsa/keys/dh1024.pem

server  # internal tun0 connection IP
ifconfig-pool-persist ipp.txt

keepalive 10 120

comp-lzo         # Compression - must be turned on at both end

status log/openvpn-status.log

verb 3  # verbose mode

Check VPN and rackspace OpenVPN for details.

Create log directory:

# cd /etc/openvpn
# mkdir -p log/
# touch log/openvpn-status.log

Restart OpenVPN (note that the /etc/init.d/openvpn script will start an openvpn server for every .conf file in /etc/openvpn/, so if you still have the tun0.conf file from above, rename it to something else than *.conf):

# /etc/init.d/openvpn restart

In Client create /etc/openvpn/client.conf as follows:

(note: you may use graphical vpn tool network-manager UI by providing the key and certificates)

dev tun
port 1194
proto udp

remote VPNSERVER_IP 1194             # VPN server IP : PORT

ca /etc/openvpn/easy-rsa/keys/ca.crt
cert /etc/openvpn/easy-rsa/keys/clientname.crt
key /etc/openvpn/easy-rsa/keys/clientname.key


verb 3

Restart OpenVPN:

# /etc/init.d/openvpn restart

Debian Server with Android / iOS devices

OpenVPN can be configured to use with Android / iOS devices.

In Debian Server, create required certificates if you have a fresh installation of ?OpenVpn:

# cd /usr/share/doc/openvpn/examples/easy-rsa/2.0
# . ./vars
# ./clean-all
# ./build-ca
# ./build-key-server server
# ./build-key client
# ./build-dh
# cd keys
# mv *.pem *.crt *.csr *.key /etc/openvpn
# cd /usr/share/doc/openvpn/examples/sample-config-files
# gunzip -c server.conf.gz > /etc/openvpn/server.conf

Modify below lines in /etc/openvpn/server.conf:

proto tcp
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS"
user nobody
group nogroup
... is Google DNS server. You may change to your preferred DNS server.

When completed, restart OpenVPN server to use the new configuration:

# /etc/init.d/openvpn restart

Create client profile file /etc/openvpn/client.ovpn and attach certificates to it:

# cd /etc/openvpn
# cp /usr/share/doc/openvpn/examples/sample-config-files/client.conf client.ovpn
# echo "set CLIENT_CERT 0" >> client.ovpn
# echo "<ca>" >> client.ovpn
# cat ca.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> client.ovpn
# echo "</ca>" >> client.ovpn
# echo "<cert>" >> client.ovpn
# cat client.crt | grep -A 100 "BEGIN CERTIFICATE" | grep -B 100 "END CERTIFICATE" >> client.ovpn
# echo "</cert>" >> client.ovpn
# echo "<key>" >> client.ovpn
# cat client.key | grep -A 100 "BEGIN PRIVATE KEY" | grep -B 100 "END PRIVATE KEY" >> client.ovpn
# echo "</key>" >> client.ovpn

Modify below lines in client profile file /etc/openvpn/client.ovpn:

proto tcp
remote YourServerIp YourServerPort
# ca ca.crt
# cert client.crt
# key client.key

where ?YourServerIp and ?YourServerPort should be changed to your server. Three lines (#ca, #cert, #key) are remarked as the required certificates were attached to the profile file instead of individual files.

e-mail or upload the client configuration file /etc/openvpn/client.ovpn to google drive in order to download to iPhone.

For iOS devices, install OpenVPN Connect client. Then transfer the client configuration file /etc/openvpn/client.ovpn to the device by e-mail or by Google Drive. Open the configuration file in Mail apps or Google Drive apps.

For Android devices, install OpenVPN Connect client. Then copy the client configuration file /etc/openvpn/client.ovpn to the storage of the device. Open the configuration file in OpenVPN apps.

Forward traffic via VPN

In Server enable runtime IP forwarding:

echo 1 > /proc/sys/net/ipv4/ip_forward

Edit /etc/sysctl.conf uncomment the following line to make it permanent:

net.ipv4.ip_forward = 1

TLDP Masquerade for details.

Execute the following command in server for testing:

iptables -A FORWARD -i eth0 -o tun0 -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -s -o eth0 -j ACCEPT
iptables -t nat -A POSTROUTING -s -o eth0 -j MASQUERADE

You may also use the rc.firewall-iptables script from TLDP Masquerade as an alternative.

In client:

# ip route add VPNSERVER_IP via LOCALGATEWAY_IP dev eth0  proto static
# ip route change default via dev tun0  proto static   //client tun0

If you use graphical client generally you may not need to execute these command.

If everying is working fine, save the iptables rules:

# iptables-save > /etc/iptables.up.rules

To restore:

# iptables-restore < /etc/iptables.up.rules

add this to startup script. Debian wiki iptables page for details.


Примечание для system.d

необходимо включить нужный конфиг в автозапуск:

systemctl enable openvpn@tun0.service

By default, all configured VPNs are started during system boot. Edit /etc/default/openvpn to start specific VPNs or to disable this behavior.

openvpn ifupdown hooks are also available for starting/stopping tunnels using /etc/network/interfaces, e.g.:

auto dsl
iface dsl inet ppp
    provider dsl-provider
    openvpn work_vpn

See /usr/share/doc/openvpn/README.Debian.gz for more information.

Application to a VPN passing through a http proxy

This part describe how to configure a VPN to pass through a http proxy, which allow only trafic on port 443 (and 80). This use the http_proxy of OpenVPN.

  1. First of all, check that the port 443 isn't already used by another service on your server.
  2. Configure OpenVPN on server side by adding port 443 and proto tcp-server to the configuration file.

  3. Configure OpenVPN on the client side by adding port 443, proto tcp-client and http-proxy 8080 to the configuration file.

Where and 8080 are IP and port of your proxy.

  1. Now you should launch OpenVPN on the server and next on the client.
  2. At this time, you should configure routes to use the VPN tunnel:
    • Remove the default route through the proxy: route del default eth0

    • Add default route through your VPN: route add default gw dev tun0

    • You should keep the route to the proxy with: route add eth0

Update your /etc/resolv.conf according to your needs.


  1. Explain how to enable the management interface (

See also