mullvad-wg.sh for Ubuntu 18.04 systemd-resolved

mullvad-wg.sh

#!/usr/bin/env bash
# SPDX-License-Identifier: GPL-2.0
#
# Copyright (C) 2016-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.

die() {
	echo "[-] Error: $1" >&2
	exit 1
}

PROGRAM="${0##*/}"
ARGS=( "$@" )
SELF="${BASH_SOURCE[0]}"
[[ $SELF == */* ]] || SELF="./$SELF"
SELF="$(cd "${SELF%/*}" && pwd -P)/${SELF##*/}"
[[ $UID == 0 ]] || exec sudo -p "[?] $PROGRAM must be run as root. Please enter the password for %u to continue: " -- "$BASH" -- "$SELF" "${ARGS[@]}"

[[ ${BASH_VERSINFO[0]} -ge 4 ]] || die "bash ${BASH_VERSINFO[0]} detected, when bash 4+ required"

type curl >/dev/null || die "Please install curl and then try again."
type jq >/dev/null || die "Please install jq and then try again."
set -e

read -p "[?] Please enter your Mullvad account number: " -r ACCOUNT

echo "[+] Contacting Mullvad API for server locations."
declare -A SERVER_ENDPOINTS
declare -A SERVER_PUBLIC_KEYS
declare -A SERVER_LOCATIONS
declare -a SERVER_CODES

RESPONSE="$(curl -LsS https://api.mullvad.net/public/relays/wireguard/v1/)" || die "Unable to connect to Mullvad API."
FIELDS="$(jq -r 'foreach .countries[] as $country (.; .; foreach $country.cities[] as $city (.; .; foreach $city.relays[] as $relay (.; .; $country.name, $city.name, $relay.hostname, $relay.public_key, $relay.ipv4_addr_in)))' <<<"$RESPONSE")" || die "Unable to parse response."
while read -r COUNTRY && read -r CITY && read -r HOSTNAME && read -r PUBKEY && read -r IPADDR; do
	CODE="${HOSTNAME%-wireguard}"
	SERVER_CODES+=( "$CODE" )
	SERVER_LOCATIONS["$CODE"]="$CITY, $COUNTRY"
	SERVER_PUBLIC_KEYS["$CODE"]="$PUBKEY"
	SERVER_ENDPOINTS["$CODE"]="$IPADDR:51820"
done <<<"$FIELDS"

shopt -s nocasematch
for CODE in "${SERVER_CODES[@]}"; do
	CONFIGURATION_FILE="/etc/wireguard/mullvad-$CODE.conf"
	[[ -f $CONFIGURATION_FILE ]] || continue
	while read -r line; do
		[[ $line =~ ^PrivateKey\ *=\ *([a-zA-Z0-9+/]{43}=)\ *$ ]] && PRIVATE_KEY="${BASH_REMATCH[1]}" && break
	done < "$CONFIGURATION_FILE"
	[[ -n $PRIVATE_KEY ]] && echo "[+] Using existing private key." && break
done
shopt -u nocasematch

if [[ -z $PRIVATE_KEY ]]; then
	echo "[+] Generating new private key."
	PRIVATE_KEY="$(wg genkey)"
fi

echo "[+] Contacting Mullvad API."
RESPONSE="$(curl -sSL https://api.mullvad.net/wg/ -d account="$ACCOUNT" --data-urlencode pubkey="$(wg pubkey <<<"$PRIVATE_KEY")")" || die "Could not talk to Mullvad API."
[[ $RESPONSE =~ ^[0-9a-f:/.,]+$ ]] || die "$RESPONSE"
ADDRESS="$RESPONSE"
DNS="193.138.219.228"

echo "[+] Writing WriteGuard configuration files."
for CODE in "${SERVER_CODES[@]}"; do
	CONFIGURATION_FILE="/etc/wireguard/mullvad-$CODE.conf"
	umask 077
	mkdir -p /etc/wireguard/
	rm -f "$CONFIGURATION_FILE.tmp"
	cat > "$CONFIGURATION_FILE.tmp" <<-_EOF
		[Interface]
		PrivateKey = $PRIVATE_KEY
		Address = $ADDRESS
		PostUp = systemd-resolve -i %i --set-dns=$DNS --set-domain=~.

		[Peer]
		PublicKey = ${SERVER_PUBLIC_KEYS["$CODE"]}
		Endpoint = ${SERVER_ENDPOINTS["$CODE"]}
		AllowedIPs = 0.0.0.0/0, ::/0
	_EOF
	mv "$CONFIGURATION_FILE.tmp" "$CONFIGURATION_FILE"
done

echo "[+] Success. The following commands may be run for connecting to Mullvad:"
for CODE in "${SERVER_CODES[@]}"; do
	echo "- ${SERVER_LOCATIONS["$CODE"]}:"
	echo "  \$ wg-quick up mullvad-$CODE"
done

echo "Please wait up to 60 seconds for your public key to be added to the servers."

As adviced in https://mullvad.net/en/guides/wireguard-and-mullvad-vpn/

DNS leaking Ubuntu 18.04 or newer (or other systems that use systemd-resolved)
Replace the 'DNS = ' line with : PostUp = systemd-resolve -i %i --set-dns=193.138.219.228 --set-domain=~.