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Install WireGuard VPN (Linux Server)

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What Is WireGuard?

WireGuard is a VPN service that can run on any Linux installation. It has a client for many popular operating systems like Windows, IOS, Android, and many others. WireGuard boasts to be more secure than OpenVPN while having over a million less lines of code, meaning that the installation is smaller and faster as well. As private VPN solutions go, this one is promising to be an easy setup and usage.

 

Objective:

This guide’s objective is to install Wireguard on Ubuntu 16.04, 18.04 or 20.04 and configure a Windows desktop PC to connect to the VPN server. This will be the most common use of WireGuard for many users. The only steps for other operating systems that differ from this guide is the initial install which can be done in 3 lines, or less and can be found at https://Wireguard.com/install.

Other uses for this software could be networking servers together into a private local network which is ideal for servers that run a remote database that should not accept requests from servers other than the ones they are meant to serve content to.

 

Installation:

It is best practice to not use the root user for anything, but instead use a sudo user that can run things as root when needed. In this guide, we will be prefixing commands with “sudo”. 

A guide to making a sudo user can be found here. This guide will assume you have made a sudo user and all commands will have the sudo in front of them when needed.

On Ubuntu 16.04 and 18.04, the command to install WireGuard is simple, however the repository for the install is not included by default, here is the 3 commands to run to add the repository and install the software.

sudo add-apt-repository ppa:wireguard/wireguard
sudo apt-get update
sudo apt-get install wireguard

On later releases of Ubuntu, the repository for WireGuard is included by default. you can simple install using the command:

sudo apt-get install wireguard

Now that Wireguard is installed, its time to start configuring it as a VPN server.

Server Configuration:

First we have to generate a public and private encryption key pair. 

sudo -i
cd /etc/wireguard/
umask 077; wg genkey | tee privatekey | wg pubkey > publickey

Now we can view them using the cat command, you will want to save the private key in a notepad or something for later use.

ls -l privatekey publickey
cat privatekey

Now we  will work on adding the VPN network adapter to allow other machines to connect through it securly. Now, using your favorite text editor, we will make some configuration changes to /etc/wireguard/wg0.conf and for the purpose of this guide, we will use nano.

sudo nano /etc/wireguard/wg0.conf

We will need to add the following to the end of the file. Please note that this is only a template and you will need to change the values as they relate to your server.

[Interface]
Address = YOURSERVERIPHERE
SaveConfig = true
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o ens3 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o ens3 -j MASQUERADE
ListenPort = 41194
PrivateKey = YOURPRIVATEKEYDETAILSHERE

[Peer]
PublicKey = YOURSERVERIPHERE
AllowedIPs = 192.168.9.2/32


# use ctrl + x to save, hit y for yes and enter to keep the same file name

Before we move on, I want to explain a few different things here. First is the IP address. This address needs to be an internal or private IP of your choosing. 192.168.xxx.xxx or 10.xxx.xxx.xxx are common. Here I set it to YOURSERVERIPHERE because all other machines are going to talk to this one to connect to the VPN. Next is the Private key in the [Interface] section. This is the key that we generated earlier.

Next thing we want to talk about is PostUp and PostDown, these are called when the VPN starts, and when it stops and allows you to forward the traffic through WireGaurd. You will need to replace ens3 with the name of your public IP addresses network adapter. If you wanted to just have an “Internal Lan” type environment or point to point, you would leave these out. The application for a point to point environment is for example, connecting a remote database server. The ListenPort can be what ever port you want, as long as it does not have something running on it already.

Moving down to the [Peer] section, we have a few things that are a bit different than software like openVPN. We have a Public Key and another internal IP address. This template is the finished product of a working configuration and you will be replacing that PublicKey value with your own. Wireguard does not allow just anyone to connect to it. You must generate a new public / private key pair and manually assign each user to the server in a new [Peer] block with a public key and the internal IP address you are assigning that connection.

We are on the home stretch now, just need to allow traffic through the firewall, assuming your using UFW:


sudo ufw allow 41194/udp

Now we need to enable IPv4 forwarding. We do this by entering the following command:

sysctl -w net.ipv4.ip_forward=1

Last but certainly not least, we start everything up. 

wg-quick up wg0

Let’s just verify everything is in good working order

sudo wg show

Now your Wireguard server is up and running. It is a good idea to reboot the server at this point, do not worry about turning Wireguard back on, it will come back automatically. Its time to use that public key we generated and get our windows PC to connect to the VPN.

A download for the official client can be found at https://wireguard.com/install/ and is what we will be using for this guide. Once installed, you should see a client like this 

Setting up the Client:

Clicking the Arrow next to the “Add Tunnel” will allow us to add an empty tunnel. Your Empty tunnel will come pre loaded with a public / private key pair which we will use.

First, lets use the information we have to configure a windows VPN client.

[Interface]
PrivateKey = YOURPRIVATEKEY
Address = YOURSERVERIP
DNS = 8.8.8.8

[Peer]
PublicKey = YOURPUBLICKEY
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = 255.255.255.255:LISTENPORT

Again in the [Interfaces] block, we are manually assigning the private ip we are going to be using in our private network, storing our private key. We are also going to assign an address to use for DNS resolution. In this example, we are using Google’s Public DNS servers. 

In the [Peer] Block, we are providing out servers information. First provide the servers public key. In the allowed IP fields, we want to allow all traffic to connect because we are using the server to connect to we addresses. Above we allowed both IPv4 and IPv6 traffic from all addresses. The last setting is the end point and it tells your client where to find the VPN server. This address and port are the ones on your server.

It is time to wrap this up by adding that public key we mentioned before in the [Peer] block for YOURSERVERIP. For reference, that was /etc/wireguard/wg0.conf.

We are now ready to Activate the VPN and enjoy our secure Virtual Private Network.