Proton VPN
Proton VPN is an open-source VPN service by the non-profit Swiss company Proton AG. It utilizes the OpenVPN protocol. Because Alpine Linux does not currently have a release for Proton VPN, using it requires connecting via either OpenVPN or Wireguard. Using Wireguard is recommended due to Proton AG's own stated preference for the service as well as Wireguard's lighter and more modern build. Setting up for Wireguard is relatively simpler because NetworkManager has native support for it, requiring fewer installations and setups.
Installation
# apk add wireguard-tools
Configuring
Login to Proton VPN and download the Wireguard config file. More information on this can be found at Proton VPN's support page. Note that the private key will only be available from the site if you download immediately after making the config file, after which the private key is replaced with asterisks. Rename the file "wg0.conf" and move it somewhere safe in your file system.
Running
To connect, run the following command. Substitute path_to_file with the full path to wherever you moved the config file.
# wg-quick up /path_to_file/wg0.conf
To enable Wireguard connecting to Proton VPN on boot, open your /etc/network/interfaces using a text editor like nano. Add this information after your auto wlan0 section:
auto wg0 iface wg0 inet static pre-up wg-quick up /path_to_file/wg0.conf
Again, substitute path_to_file with your own relevant information.