Title: How to use WireGuard VPN on Guix

	Title: How to use WireGuard VPN on Guix
	Author: Solène
	Date: 22 May 2021
	Tags: guix vpn
	Description:

	# Introduction

	Today I had to setup a Wireguard tunnel on my Guix computer (my email
	server is only reachable from Wireguard) and I struggled a bit to
	understand from the official documentation how to put the pieces
	together.

	In Guix (the operating system, and not the foreign Guix on an existing
	distribution) you certainly have a /etc/config.scm file that defines
	your system. You will have to add the Wireguard configuration in it
	after generating a private/public keys for your Wireguard.

	Guix project website
	Guix Wireguard VPN documentation

	# Key generation

	In order to generate Wireguard keys, install the package Wireguard with
	"guix install wireguard".

	```shell commands
	# umask 077 # this is so to make files only readable by root
	# install -d -o root -g root -m 700 /etc/wireguard
	# wg genkey > /etc/wireguard/private.key
	# wg pubkey < /etc/wireguard/private.key > /etc/wireguard/public
	```

	# Configuration

	Edit your /etc/config.scm file, in your "(services)" definition, you
	will define your VPN service. In this example, my Wireguard server is
	hosted at 192.168.10.120 on port 4433, my system has the IP address
	192.168.5.1, I also defines my public key but my private key is
	automatically picked up from /etc/wireguard/private.key

	```config.scm example
	(services (append (list
	(service wireguard-service-type
	(wireguard-configuration
	(addresses '("192.168.5.1/24"))
	(peers
	(list
	(wireguard-peer
	(name "myserver")
	(endpoint "192.168.10.120:4433")
	(public-key "z+SCmAMgNNvkeaD0nfBu4fCrhk8FaNCa1/HnnbD21wE=")
	(allowed-ips '("192.168.5.0/24"))))))))
	%desktop-services))
	```

	If you have the default "(services %desktop-services)" you need to use
	"(append " to merge %desktop-services and new services all defined in a
	"(list ... )" definition.

	The "allowed-ips" field is important, Guix will automatically make
	routes to these networks through the Wireguard interface, if you want
	to route everything then use "0.0.0.0/0" (you will require a NAT on the
	other side) and Guix will make the required work to pass all your
	traffic through the VPN.

	At the top of the config.scm file, you must add "vpn" in the services
	modules, like this:

	```config.scm services modules
	# I added vpn to the list
	(use-service-modules vpn desktop networking ssh xorg)
	```

	Once you made the changes, you can use "guix system reconfigure" to
	make the changes, if you do multiples reconfigure it seems Wireguard
	doesn't reload correctly, you may have to use "herd restart
	wireguard-wg0" to properly get the new settings (seems a bug?).

	# Conclusion

	As usual, setting Wireguard is easy but the functional way make it a
	bit different. It took me some time to figure out where I had to
	define the Wireguard service in the configuration file.