Category: Cybersecurity

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Read this same article on the Rocky Linux Documentation website

Introduction

WireGuard is a free and open-source peer-to-peer (P2P) Virtual Private Network (VPN). It is a lightweight and secure modern alternative to conventional VPNs with large codebases that rely on TCP connections. Since WireGuard is a P2P VPN, each computer added to the WireGuard network communicates directly with each other. This guide uses a hub-spoke model, with a WireGuard peer assigned a public IP address as a gateway to pass all traffic. This allows WireGuard traffic to bypass Carrier Grade NAT (CGNAT) without enabling port-forwarding on your router. This requires a Rocky Linux system with a public IP address. The easiest way to achieve this is to spin up a virtual private server (VPS) through a cloud provider of your choice. At the time of writing, Google Cloud Platform offers a free tier for its e2-micro instances.

Prerequisites and assumptions

The minimum requirements for this procedure are the following:

• The ability to run commands as the root user or use sudo to elevate privileges
• A Rocky Linux system with a publicly accessible IP address

Installing WireGuard

Install Extra Packages for Enterprise Linux (EPEL):

sudo dnf install epel-release -y

Upgrade system packages:

sudo dnf upgrade -y

Install WireGuard:

sudo dnf install wireguard-tools -y

Configuring WireGuard Server

Create a folder to put your WireGuard configuration files and keys:

sudo mkdir -p /etc/wireguard

Create a configuration file with a name of your choice ending with the .conf extension:

Note

You can create multiple WireGuard VPN tunnels on the same machine, each using a different configuration file, network address, and UDP port.

sudo touch /etc/wireguard/wg0.conf

Generate a new private and public key pair for the WireGuard server:

wg genkey | sudo tee /etc/wireguard/wg0 | wg pubkey | sudo tee /etc/wireguard/wg0.pub

Edit the configuration file with your editor of choice.

sudo vi /etc/wireguard/wg0.conf

Paste the following:

[Interface]
PrivateKey = server_privatekey
Address = x.x.x.x/24
ListenPort = 51820

You must replace the server_privatekey with the private key generated earlier. You can view the private key with:

sudo cat /etc/wireguard/wg0

Next, you will need to replace x.x.x.x/24 with a network address within the private IP address range defined by RFC 1918. The network address used in this guide is 10.255.255.0/24.

Finally, you can choose any UDP port to accept connections with WireGuard VPN. UDP port 51820 is used for the purposes of this guide.

Enable IP forwarding

IP forwarding allows the routing of packets between networks. This allows internal devices to communicate with each other through the WireGuard tunnel:

Turn on IP forwarding for IPv4 and IPv6:

sudo sysctl -w net.ipv4.ip_forward=1 && sudo sysctl -w net.ipv6.conf.all.forwarding=1

Configure firewalld

Install firewalld:

sudo dnf install firewalld -y

After installing firewalld, enable it:

sudo systemctl enable --now firewalld

Create a permanent firewall rule allowing traffic on UDP port 51820 in the public zone:

sudo firewall-cmd --permanent --zone=public --add-port=51820/udp

Next, traffic from the WireGuard interface will be allowed to other interfaces in the internal zone.

sudo firewall-cmd --permanent --add-interface=wg0 --zone=internal

Add a firewall rule to enable IP masquerading on internal traffic. This means that packets sent between peers will replace the packet IP address with the server’s IP address:

sudo firewall-cmd --permanent --zone=internal --add-masquerade

Finally, reload firewalld:

sudo firewall-cmd --reload

Configure WireGuard peer

Since all computers in a WireGuard network are technically peers, this process is nearly identical to configuring the WireGuard server, but with slight differences.

Create a folder to put your WireGuard configuration files and keys:

sudo mkdir -p /etc/wireguard

Create a configuration file, giving it a name of your choice, ending with the .conf extension:

sudo touch /etc/wireguard/wg0.conf

Generate a new private and public key pair:

wg genkey | sudo tee /etc/wireguard/wg0 | wg pubkey | sudo tee /etc/wireguard/wg0.pub

Edit the configuration file with your editor of choice, adding this content:

[Interface]
PrivateKey = peer_privatekey
Address = 10.255.255.2/24

[Peer]
PublicKey = server_publickey
AllowedIPs = 10.255.255.1/24
Endpoint = serverip:51820
PersistentKeepalive = 25

Replace peer_privatekey with the peer’s private key stored in /etc/wireguard/wg0 on the peer.

You can use this command to output the key so you can copy it:

sudo cat /etc/wireguard/wg0

Replace server_publickey with the server’s public key stored in /etc/wireguard/wg0.pub on the server.

You can use this command to output the key so you can copy it:

sudo cat /etc/wireguard/wg0.pub

Replace serverip with the public IP of the WireGuard server.

You can find the server’s public IP address using the following command on the server:

ip a | grep inet

The peer’s configuration file now includes a PersistentKeepalive = 25 rule. This rule tells the peer to ping the WireGuard server every 25 seconds to maintain the VPN tunnel’s connection. Without this setting, the VPN tunnel will time out after inactivity.

Enable WireGuard VPN

To enable WireGuard, you will run the following command on both the server and peer:

sudo systemctl enable wg-quick@wg0

Then start the VPN by running this command on both the server and peer:

sudo systemctl start wg-quick@wg0

Add the client key to the WireGuard server configuration

Output the peer’s public key and copy it:

sudo cat /etc/wireguard/wg0.pub

On the server, run the following command, replacing peer_publickey with the peer’s public key:

sudo wg set wg0 peer peer_publickey allowed-ips 10.255.255.2

Using wg set only makes temporary changes to the WireGuard interface. For permanent configuration changes you can manually edit the configuration file and add the peer. You will need to reload the WireGuard interface after making any permanent configuration changes.

Edit the server’s configuration file with your editor of choice.

sudo vi /etc/wireguard/wg0.conf

Add the peer to configuration file. The contents should look similar to below:

[Interface]
PrivateKey = +Eo5oVjt+d3XWvFWYcOChaLroGj5vapdXKH8UZ2T2Fc=
Address = 10.255.255.1/24
ListenPort = 51820

[Peer]
PublicKey = 1vSho8NvECkG1PVVk7avZWDmrd2VGZ2xTPaNe5+XKSg=
AllowedIps = 10.255.255.2/32

Bring interface down:

sudo wg-quick down wg0

Bring interface up:

sudo wg-quick up wg0

View WireGuard interfaces and test connectivity

You can view WireGuard information on both the server and peer with:

sudo wg

You can test connectivity by sending a ping to the server from the peer:

ping 10.255.255.1

Conclusion

Following this guide, you have successfully set up a WireGuard VPN using the hub-spoke model. This configuration provides a secure, modern, and efficient way to connect multiple devices across the internet. Check the official WireGuard website.

Articles to Read Next

How to Setup WireGuard VPN on Rocky 9 Linux

Secure Remote Support on LAN with x11vnc over SSH on Rocky Linux

How to Install Virtual Box and Answering “What is a Hypervisor?”

How to Enable Bidirectional Shared Clipboard on VirtualBox VM

How to Create a Linux VM with VirtualBox

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