Installing OpenVPN on a Scaleway Instance running Ubuntu 24.04

vpn

OpenVPN

Ubuntu

Reviewed on January 06, 2025

Learn how to install and configure OpenVPN on Ubuntu 24.04 LTS with this comprehensive guide. Follow our step-by-step instructions to establish a secure VPN connection via your Scaleway Instance with ease.

Before you start

To complete the actions presented below, you must have:

A Scaleway account logged into the console
Owner status or IAM permissions allowing you to perform actions in the intended Organization
An SSH key
An Instance running on Ubuntu 24.04 LTS

Installing OpenVPN and Easy-RSA

Connect to your Instance via SSH.
```
root@<YOUR_INSTANCE_IP>
```
Update the package list and upgrade already installed packages:
```
apt update
apt upgrade -y
```
Install OpenVPN and Easy-RSA using apt:
```
apt install -y openvpn easy-rsa
```

Setting up the Certificate Authority (CA)

Create a directory for Easy-RSA and navigate to it:
```
mkdir -p ~/openvpn-ca
cd ~/openvpn-ca
```

Initialize the Public Key Infrastructure (PKI):

cp -r /usr/share/easy-rsa/* /etc/openvpn/easy-rsa/
cd /etc/openvpn/easy-rsa/
./easyrsa init-pki

Build the Certificate Authority (CA):
```
./easyrsa build-ca
```
You will be prompted to set a passphrase and provide a Common Name (e.g., "OpenVPN-CA").

Generating server and client certificates

Generate the server certificate and key:
```
./easyrsa gen-req server nopass
./easyrsa sign-req server server
```
Approve the signing request when prompted.
Generate Diffie-Hellman parameters:
```
./easyrsa gen-dh
```
Generate a shared secret for additional security:
```
openvpn --genkey secret /etc/openvpn/ta.key
```

Configuring the OpenVPN Server

Copy the necessary files to the OpenVPN directory:

cp pki/ca.crt pki/private/server.key pki/issued/server.crt /etc/openvpn/
cp /etc/openvpn/easy-rsa/pki/dh.pem /etc/openvpn/
cp /etc/openvpn/ta.key /etc/openvpn/

Create the OpenVPN server configuration file:
```
nano /etc/openvpn/server.conf
```

Add the following configuration:

port 1194
proto udp
dev tun
ca ca.crt
cert server.crt
key server.key
dh dh.pem
auth SHA256
tls-auth ta.key 0
server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt
push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"
keepalive 10 120
cipher AES-256-GCM
user nobody
group nogroup
persist-key
persist-tun
status openvpn-status.log
log-append /var/log/openvpn.log
verb 3

Save and exit the editor.

Enabling IP forwarding and configuring the firewall

Enable IP forwarding:

echo 'net.ipv4.ip_forward=1' | tee -a /etc/sysctl.conf
sysctl -p

Configure the firewall (UFW):
```
ufw allow 1194/udp
ufw allow OpenSSH
```
Edit the UFW configuration to allow forwarding:
```
nano /etc/ufw/before.rules
```

Add the following lines before the *filter line:

*nat
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
COMMIT

Save and exit, then reload UFW:
```
ufw disable
ufw enable
```

Starting the OpenVPN server

Start and enable the OpenVPN service:

systemctl start openvpn@server
systemctl enable openvpn@server

Check the status of the OpenVPN service:
```
systemctl status openvpn@server
```
Ensure it is active and running.

Generating client configuration

Generate client certificates:

cd /etc/openvpn/easy-rsa/
./easyrsa gen-req client1 nopass
./easyrsa sign-req client client1

Approve the signing request when prompted.

Create the client configuration file: On your server, create a new client configuration file named client1.ovpn:
```
nano ~/client1.ovpn
```

Add the following configuration in the file, replacing your_server_ip_or_domain with your server's IP address or domain name:

client
dev tun
proto udp
remote your_server_ip_or_domain 1194
resolv-retry infinite
nobind
persist-key
persist-tun
remote-cert-tls server
auth SHA256
cipher AES-256-GCM
verb 3
<ca>
-----BEGIN CERTIFICATE-----
# Insert the content of /etc/openvpn/ca.crt here
-----END CERTIFICATE-----
</ca>
<cert>
-----BEGIN CERTIFICATE-----
# Insert the content of /etc/openvpn/easy-rsa/pki/issued/client1.crt here
-----END CERTIFICATE-----
</cert>
<key>
-----BEGIN PRIVATE KEY-----
# Insert the content of /etc/openvpn/easy-rsa/pki/private/client1.key here
-----END PRIVATE KEY-----
</key>
<tls-auth>
-----BEGIN OpenVPN Static key V1-----
# Insert the content of /etc/openvpn/ta.key here
-----END OpenVPN Static key V1-----
</tls-auth>
key-direction 1

Note

Replace the placeholder text (e.g., # Insert the content of /etc/openvpn/ca.crt here) with the actual contents of the respective files. You can use the cat command to display the contents of each file and then copy and paste them into the appropriate sections of the client1.ovpn file.

For example:
```
cat /etc/openvpn/ca.crt
```

Copy the output and paste it between the <ca> and </ca> tags in the client1.ovpn file.

Transfer the client configuration file to the client device: Use a secure method to transfer the client1.ovpn file to the device you intend to use as a client. You can use scp (secure copy) for this purpose:
```
scp ~/client1.ovpn user@client_device_ip:/path/to/destination/
```
Replace user with your username on the client device, client_device_ip with the client's IP address, and /path/to/destination/ with the desired directory on the client device.
Install OpenVPN on the client device: Ensure that the OpenVPN client is installed on your client device. Installation methods vary depending on the operating system:
- Linux:
```
apt update
apt install -y openvpn
```
- Windows:
  
  Download and install the OpenVPN client from the official website.
- macOS:
  
  Download and install Tunnelblick, a free OpenVPN client for macOS.
Connect to the VPN:
- Linux:
  
  Use the following command to start the VPN connection:
```
openvpn --config /path/to/client1.ovpn
```
- Windows/macOS:
  
  Import the client1.ovpn file into your OpenVPN client application and initiate the connection through the application's interface.
Verify the connection: Once connected, verify that your public IP address matches the VPN server's IP address, indicating that your internet traffic is being routed through the VPN. You can check your public IP address by visiting WhatIsMyIP.com or a similar service.

Your OpenVPN server is now configured on your Ubuntu 24.04 LTS instance, and your client device is set up to connect securely.

Maintenance

For ongoing maintenance, remember to renew your Let's Encrypt certificates regularly (they expire every 90 days). You can automate this process with a cron job:

echo "0 0 1 */2 * certbot renew --quiet" | tee -a /etc/crontab

This cron job runs the certbot renew command on the first day of every second month at midnight.

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