How to Install and Configure OpenVPN on Windows 10

Introduction

In this blog article we are going to discuss about How to Install and Configure OpenVPN on Windows 10. A VPN is short form of virtual private network, which gives us a privacy, anonymity and security over public internet. A VPN service masks our ISP IP so your online actions are virtually untraceable. A VPN can also be used to connect computers to isolated remote computer networks that is usually inaccessible, by using the Internet or another intermediate network.

We can define OpenVPN as a full-featured SSL VPN. OpenVPN uses OSI layer 2 or 3 secure network extension using the industry standard SSL/TLS protocol. OpenVPN supports flexible client authentication methods based on certificates, smart cards and username/password credentials. OpenVPN is not a web application proxy and does not operate through a web browser. OpenVPN server process over a single TCP or UDP port. The default port number is 1194. OpenVPN 2.3 includes a large number of improvements, including full IPv6 support and PolarSSL support.

OpenVPN is also the name of the open source project started by our co-founder and which uses the GPL license. He developed the OpenVPN project that used to encrypt and secure point-to-point or site-to-site connection between two machines over the public Internet. In other word using OpenVPN we can create a secure Private network over public Internet and will have Remote access to internal services of your IT infrastructure.

Use Cases of OpenVPN

Secure Remote Access
Site-to-site , Users-to-Site or Users-to-Users connectivity to bring networks together
Protect screen sharing and remote desktop communications
Encrypt sensitive IoT communications
Secure Access to Cloud-Based Systems

OpenVPN available as Below.

1. OpenVPN Community Edition, which is a free and open-source version
2. OpenVPN Access Server (OpenVPN-AS), is based on the Community Edition, but provides additional paid and proprietary features like LDAP integration, Easy Management Admin Portal ,cluster option etc.
3. OpenVPN-as-a-Service, solution eliminates the need for VPN server installation. By Purchasing OpenVPN Cloud we can simply connect to our hosted service with regions around the globe.

Apart from OpenVPN Community Edition, the other two OpenVPN editions has Economical licensing model that is based only on the number of simultaneous VPN connecting users or devices.

The OpenVPN Community Edition totally free to use and there is no user limitations. OpenVPN community edition server can be installed on Linux or Windows Based systems.

OpenVPN for Windows

It can be installed from the self-installing exe file which is called OpenVPN GUI. OpenVPN GUI is a graphical fronted for OpenVPN running on Windows. It creates an icon in the notification area from which you can control OpenVPN to start/stop your VPN tunnels, view the log and do other useful things.

OpenVPN Connect client

It is the OpenVPN client software packages installing on client PC. This client package used to connect to the OpenVPN server. OpenVPN Connect client supported on Windows, Linux, MacOS, IOS and Android.

Setting Up OpenVPN Server.

In this article will show you how to Setup up a OpenVPN Server ( Community Edition) On Windows 10 to forward incoming traffic to the internet, then route the responses back to the client. This is a Users-to-Site Model.Which means settings up a OpenVPN  Server to tunnel clients internet traffic through OpenVPN server. Those clients that successfully connected to the OpenVPN server will have their ISP IP Address will show as servers Public IP address.Commonly, a VPN tunnel is used to privately access the internet, evading censorship or Geo location by shielding your computer’s web traffic when connecting through entrusted hotspots, or connections.

Section 1. Installing OpenVPN Server

Let’s get Started. First thing is Download the latest Windows 64-bit MSI installer for OpenVPN Community edition from official OpenVPN Website, under community section.

The OpenVPN executable should be installed on both server and client machines, since the single executable provides both client and server functions.

Once Downloaded right click the installer exe file and choose install option.

The following screen will appear, click “Customise”  to start the installation.

Make sure to choose all features by clicking the icon next to each features and selecting the option “Entire feature will be installed on local hard drive”.  Below are the two features which will not be installed by default and we need to select during install.

Openssl utilities , EasyRSA 3 Certificate Management scripts

OpenVPN service.

Click Install Now button after selecting all features.

The install will get completed and we will get below screen. Click Close. The default  install location will be C:\Program Files\OpenVPN

We will get a warning message as ” No readable connection profiles ( config files ) found. Its fine , click OK.

This Completes the OpenVPN MSI Package install. After the install,  Under Windows 10 “Network and Internet ” settings  >>  Under Ethernet >> Change adaptor options >> We can see a new network adaptor named OpenVPN TAP device created.

Now we can manage  the OpenVPN service either  from Windows Start Menu -> Control Panel -> Administrative Tools -> Services section.

As of OpenVPN version 2.5.0,While starting the OpenVPN wrapper service the OpenVPN will look for .ovpn configuration file under folder “C:\Program Files\OpenVPN\config-auto” to auto-start OpenVPN service when ever our Windows 10 reboots.

Another option to start/stop OpenVPN service is  Click on Windows hidden notification area from task bar , there we can see the OpenVPN icon, right click on it and you will see multiple options including Connect and Disconnect.

If you don’t see the OpenVPN icon in the Windows task bar notification area, double click the OpenVPN icon available in the desktop and that will make the OpenVPN icon available at the windows task bar notification area.

For better understanding refer below screenshot.

As I mentioned earlier As of OpenVPN version 2.5.0,  when we start the OpenVPN service using the GUI component under windows task bar notification area, the OpenVPN will look for .ovpn configuration file under folder “C:\Program Files\OpenVPN\config”.

This Concludes the OpenVPN Package install on Windows 10 for Server and for the Client PC. Now lets move to the next section.

Section 2. Setup Master Certificate Authority (CA) and Generate Certificates and keys for OpenVPN Server and Clients.

OpenVPN uses public-key infrastructure (PKI) for certificate generation and Management. It is the technology behind digital certificates. There for, PKI is the technology that allows you to encrypt data, digitally sign documents, and authenticate yourself using certificates.

The PKI consists of:

1. A separate certificate (also known as a public key) and private key for the server and each client, and
2. A master Certificate Authority (CA) certificate and key which is used to sign each of the server and client certificates.

For PKI management,  The latest version of OpenVPN packages provided  easy-rsa 3, a set of scripts which is bundled with OpenVPN MSI.

The easy-rsa3 scripts folder location should be “C:\Program Files\OpenVPN\easy-rsa”.  Also the Easy-RSA 3 runs POSIX shell code, so use on Windows has some additional
requirements such as  an OpenSSL installation, and a usable shell environment but  Windows packages of EasyRSA 3.0.7+ include an OpenSSL binary and libraries that will be used by default. So basically we don’t need to perform the OpenSSL install separately in our Windows Install.

Additionally The Easy-RSA 3 Windows release includes a ready-to-use shell environment  where we can run the commands that needed to issue SSL/TSL certificates. So lets proceed with the SSL/TLS certificate creation along with CA certificate using easy-rsa3 scripts.

First thing is go the folder “C:\Program Files\OpenVPN\easy-rsa” using Windows File explorer.  Copy the file named “vars.example” to file named “vars“.

The “vars “ file contains built-in  Easy-RSA configuration settings.  The default settings are fine unless if we need any custom changes.  Few configurable options given in below table.

So if you need to edit above default values, un-comment corresponding lines and make necessary changes. The “var”  also have other configurable options but I only mentioned few important variables.  So in our case we are fine with the default values and the default values  will be used  during certificate generation.

Now Open the windows command prompt and go the directory “C:\Program Files\OpenVPN\easy-rsa”.  After that Launch EasyRSA shell. For that issue below commands.

Now we have entered the easy-rsa3 shell prompt and from there we will be able to issue easy-rsa3 scripts. Attached  a screenshot for reference.

Now Initiate the Public Key Infrastructure PKI directory. For that issue below command in the EasyRSA Shell.

Below the screenshot for reference. From there we can see the PKI directory is set to “C:\Program Files\OpenVPN\easy-rsa\pki”

Now build the certificate authority (CA ) key using the command below.  This CA root certificate file later will be used to sign other certificates and keys. The option “nopass”  we  used is to disable password locking the CA certificate.

The command will be asked to enter the common name. Here I entered my VPN server Hostname which is OPENVPNSERVER, and it is a common practice. Here we are free to use any name or values.  Also the created the CA certificate will be saved to folder “C:\Program Files\OpenVPN\easy-rsa\pki” with file name as “ca.crt”.  Refer below screenshot.

Now Build a server certificate and key using below command.   Here Replace <SERVER> with your own server name.  Also I used Option nopass for disabling password locking the key.

Attached a screenshot for your reference.  The issued server certificate will be in the folder “C:\Program Files\OpenVPN\easy-rsa\pki\issued” with file name as SERVER.crt.

After that we can verify the issued server certificate using below openssl command in the EasyRSA shell itself. The Status Ok indicate that the certificate is fine.

Now Build a client certificate and key using below command. From that Replace <CLIENT> with your client name.  Also used Option nopass for disabling password locking the key.

Attached a screenshot for your reference. The issued client certificate will also be saved to folder “C:\Program Files\OpenVPN\easy-rsa\pki\issued” with file name as “CLIENT.crt”.

After that we can verify the issued client certificate using below openssl command. The Ok indicate that the certificate is fine.

This Completed the CA certificate, Sever and Client Certificate Generation along with Key. These keys will be used to authenticate between OpenVPN server and with the Client.

Now Generate a shared-secret key that is used in addition to the standard RSA certificate/key. The file name is tls-auth.key.

Using this key we enable  tls-auth directive Which adds an additional HMAC signature to all SSL/TLS handshake packets for integrity verification. Any UDP packet not bearing the correct HMAC signature can be dropped without further processing.

Enabling the tls-auth will protect us from

• DoS attacks or port flooding on the OpenVPN UDP port.
• Port scanning to determine which server UDP ports are in a listening state.
• Buffer overflow vulnerabilities in the SSL/TLS implementation.
• SSL/TLS handshake initiations from unauthorised machines.

So first Download Easy-TLS   using the GitHub link https://github.com/TinCanTech/easy-tls. It is an Easy-RSA extension utility that we are using to generate tls-auth key.

Click the Download zip option which is available under code tab.  Refer below screenshot.

After that unzip the easy-tls-master folder and copy the files named “easytls”and “easytls-openssl.cnf” file to “C:\Program Files\OpenVPN\easy-rsa” directory. Check below screenshot for reference.

Now go back to the EasyRSA  shell prompt and issue below command. This will initialise the easy-tls script utility.

Now after that generate the tls-auth key using below command.

The command will generate the tls-auth key file named “tls-auth.key”  under the folder “C:\Program Files\OpenVPN\easy-rsa\pki\easytls”.  Refer below screenshot.

Now we need to Generate Diffie Hellman parameters.

Diffie Hellman parameters must be generated for the OpenVPN server.

These parameters define how OpenSSL performs the Diffie-Hellman (DH) key-exchange. Diffie–Hellman key exchange is a method of securely exchanging cryptographic keys over a public channel

Issue below command for generating Diffie Hellman parameters from the EasyRSA shell.

The command will create the DH file under folder “C:\Program Files\OpenVPN\easy-rsa\pki” with file name as “dh.pem”.  Refer below screenshot.

This completes the generation of necessary SSL/TLS key files needed for OpenVPN service. We will be able to find the created files under below folders.

Refer below screenshot.

Also below is the short explanation of the relevant files.

Now its the time to copy Certificate files ca.crt, CLIENT.crt, CLIENT.key  and tls-auth.key  from OpenVPN server to the OpenVPN client PC.  Make sure to copy secret files over a secure channel like SFTP.

Okay, this completes the creation of SSL/TLS certificates for the OpenVPN service. Now lets move to the next section.

Section 3 . Create configuration files for server

In this section, we create the OpenVPN Server configuration file and Make Necessary changes in it.

First Open Windows Explorer and go the folder “C:\Program Files\OpenVPN\sample-config” and copy file named “server.ovpn” to “C:\Program Files\OpenVPN\config”.

Refer Below Screenshot.

Now open the config file using any Text editor and make changes to below values accordingly.

In that first four values defines the location of ca, cert , key and Diffie hellman parameters certificate locations.

The Next three lines enforce the clients to redirect their all traffic through OpenVPN server once they successfully connected to OpenVPN server.

Using “tls-auth” parameter, we enable HMAC firewall. Its an extra layer of security used to prevent DDos attack.

The last one “data-ciphers AES-256-CBC” enables a cryptographic cipher.

Refer below screenshots and then you will get an idea about how these parameters looks in server.ovpn config file.

This Completes the OpenVPN config file Setup. Now open the UDP Port 1194 in the Windows firewall using below power shell command.

Now start the OpenVPN server service by click on Windows Show hidden icons section >> right click the OpenVPN icon >> Choose Connect.

The OpenVPN service will start automatically and you will see a green colour inside OpenVPN icon. This means that our OpenVPN service is running.

Another Option to confirm the running of OpenVPN service is , take windows cmd and list all network interfaces. We will see now the OpenVPN TUN/TAP interface is assigned with private IP 10.8.0.1, which is the default private IP address range assigned to server and with clients as per the config settings.

Section 4. Enable Internet Connection Sharing (ICS) in Windows 10

As I mentioned in the introduction section we are setting up our OpenVPN server , to route clients all IP traffic such as Web browsing and DNS lookups through VPN Server itself. For that we need to share  the  public internet through OpenVPN server Public Interface that already have internet access to OpenVPN TUN/TAP Network interface.

• So lets see how this can be accomplished. For that first go to the windows services section and Right-click “Routing and Remote Access” service. Choose Properties and make the startup type as Automatic. After that start the service.
• After that go to VPN Server “Network and Internet ” settings >> Under Ethernet >> Change adaptor options >>  Right click the Network Adaptor name which is having Public Internet access and choose properties.

• Choose Sharing tab and from there Tick the box “Allow other network users to connect through this computer’s Internet connection” option
• From the drop-down list select “OpenVPN Tap-Windows6”, or whatever is the connection name of your TAP server connection.
• Also if you needed you can tick the box next to ” Allow other network users to control or disable the shared internet connection” option
• Click Ok and confirm the changes

• Now edit the below registry  key value. For that run the  “regedit” in Windows Run.

Okay, this completes Enable Internet Connection Sharing (ICS) in Windows 10. Now lets move to the next section. Also reconnect the OpenVPN connection again to take effect the changes.

Section 5 . Setup OpenVPN Client.

In this section we first install the OpenVPN MSI installer on Client PC like Windows 10. After that we will setup OpenVPN client config files.  Finally start the the OpenVPN connection and test it out.

Section 5 a . OpenVPN Client MSI Install

For OpenVPN MSI installation on Client PC, follow the same steps described on Section 1. The OpenVPN Community Edition MSI Installer can be used on both Server side and with the client side.

After the OpenVPN MSI installation. Open Windows Explorer and go the folder “C:\Program Files\OpenVPN\sample-config” and copy file named “client.ovpn” to “C:\Program Files\OpenVPN\config”.

Move already downloaded ca.crt, CLIENT.crt, CLIENT.key and tls-auth.key to folder “C:\Program Files\OpenVPN\config”.

Refer below screenshot for better understanding on file structure.

Section 5 b . Configure Client Config File.

Go to the folder “C:\Program Files\OpenVPN\config” and open client.ovpn file using any text editor and define below parameters accordingly.

In that first value defines The hostname/IP and port of the OpenVPN server

The Next three ca, cert , key values defines the location of CA and client certificate locations.

Using “remote-cert-tls server” , the OpenVPN client will verify the server certificate extendedKeyUsage.

Using “tls-auth” parameter, we enable HMAC firewall. Its an extra layer of security used to prevent DDos attack.

The last one “cipher AES-256-CBC” enables a cryptographic cipher.

Below picture shows how these parameters looks in the client config file.

This Completes the Client Setup. Now test the VPN Connection from client side. Make sure to open UDP port 1194 in the client side windows firewall too.

Section 5 c . Testing the OpenVPN connection.

Under windows Hidden Notification area , right click on OpenVPN icon and Click Connect.

The OpenVPN connection will establish automatically. After the successful connection , try to ping to the private IP of OpenVPN server and make sure its reachable. Also test the internet connection of your client PC.

Also on a Successfully connected OpenVPN Client PC, if we lookup the what is my IP on web browser, we will see its our VPN Server IP. This means that all our web traffic is routing through OpenVPN server.

Conclusion.

We have successfully completed the OpenVPN setup On Windows 10 and successfully connected from a Windows 10 OpenVPN client PC. Also we have seen how to route all IP traffic from client side through OpenVPN server. I hope this article is informative. Leave your thoughts at the comment box.