Openvpn autostart on debian 12 cli client

To configure an OpenVPN client to autostart on a Debian 12 CLI system using systemd, follow these steps: Place the OpenVPN configuration file.

Move your OpenVPN client configuration file (e.g., client.ovpn) to the /etc/openvpn/ directory and rename it with a .conf extension (e.g., client.conf).

sudo mv /path/to/your/client.ovpn /etc/openvpn/client.conf

Edit the configuration file (if necessary).

If your OpenVPN configuration requires username and password authentication, you might need to modify the auth-user-pass line in your .conf file to point to a credentials file.

sudo nano /etc/openvpn/client.conf

Change auth-user-pass to auth-user-pass /etc/openvpn/pass.txt (or your chosen path and filename for the credentials file). Create a credentials file (if needed).
If you modified auth-user-pass in the previous step, create a file containing your username and password in the specified location (e.g., /etc/openvpn/pass.txt).

sudo nano /etc/openvpn/pass.txt

Enter your OpenVPN username on the first line and your password on the second line. Save and close the file. Enable the OpenVPN service.   
Use systemctl to enable the OpenVPN service for your specific configuration file. Replace client with the name of your .conf file (without the .conf extension).

sudo systemctl enable openvpn@client.service

Reload systemd daemons. Reload systemd to recognize the newly enabled service.

sudo systemctl daemon-reload

Start the OpenVPN service. Manually start the service to ensure it’s working correctly.

sudo systemctl start openvpn@client.service

Verify the connection. Check your external IP address or the tun0 interface to confirm the VPN connection is established.

curl ifconfig.co
ip a show tun0

After these steps, your OpenVPN client will automatically connect on system boot.