Various tools can be used on Kerlink gateways to establish secure connections.
They can be used just like on any linux system.

• openvpn
• strongswan
• tailscale
• wireguard

They are available for installation using apt:

sudo apt update && sudo apt install <packageName>

OpenVPN

First, install OpenVPN:

sudo apt install openvpn

Please refer to the offical OpenVPN documentation to specify your VPN configuration.
Then, put it in /etc/openvpn/client:

sudo vi /etc/openvpn/client/name.conf # you can use any name, but it must end in `.conf'

A .ovpn file is compatible. It can simply be renamed using
mv name.ovpn name.conf

Enable and start the VPN using systemd:

sudo systemctl enable --now openvpn-client@name # replace `name' with the file name in step 2, without `.conf'

You can monitor the status and logs of the VPN using systemd:

sudo systemctl status openvpn-client@name
sudo journalctl -fu openvpn-client@name

The VPN will automatically start at boot time. You can review the IP address and routing table using these commands:

sudo ip addr
sudo ip route

redirect-gateway rule from Openvpn server may lead to unexpected behavior, please remove it from server or ignore it in client configuration using:
pull-filter ignore redirect-gateway

Tailscale

A dedicated page is available to set up a Tailscale connection. Please follow the instructions described on this page.