Wireguard Installation on PC Engines APU with Ubuntu 18.

• Install hardware, see Ubuntu on PC Engines
• Configure networking: /etc/netplan/01-netcfg.yaml

  # This file describes the network interfaces available on your system
  # For more information, see netplan(5).
  network:
    version: 2
    renderer: networkd
    ethernets:
      enp1s0:
        addresses:
          - 192.168.1.20/24
        gateway4: 192.168.1.1
        nameservers:
            search: [lan]
            addresses: [192.168.1.53]
  

• Apply settings:

  netplan apply

• Install netfilter-persistent:

  apt install iptables-persistent

• Configure iptables:

  iptables -A ...
  netfilter-persistent save

• Install PPA and Wireguard:

  sudo apt-get install software-properties-common
  sudo add-apt-repository ppa:wireguard/wireguard
  sudo apt update
  sudo apt install wireguard qrencode

• Reboot to confirm the wireguard automatically loads.

  ip link add dev wg0 type wireguard
  lsmod | grep wire

• Generate keys:

  umask 077
  wg genkey | tee privatekey | wg pubkey > publickey

• Configure Wireguard /etc/wireguard/wg0.conf:

  [Interface]
  Address = 192.168.2.1/24
  SaveConfig = true
  PostUp = /usr/local/bin/wg-iptables.sh %i up
  PreDown = /usr/local/bin/wg-iptables.sh %i down
  ListenPort = <random port>
  PrivateKey = <privatekey>

• Change mod bits:

  chmod 600 /etc/wireguard/wg0.conf

• Add iptables script /usr/local/bin/wg-iptables.sh

  #!/bin/bash
  
  WGINT=$1
  OUTINT=enp1s0
  ACTION=$2
  
  case "${ACTION}" in
  	up)
  		iptables  -A FORWARD -i ${WGINT} -o ${OUTINT} -j ACCEPT
                  ip6tables -A FORWARD -i ${WGINT} -o ${OUTINT} -j ACCEPT
                  iptables  -t nat -A POSTROUTING -o ${OUTINT} -j MASQUERADE
                  ip6tables -t nat -A POSTROUTING -o ${OUTINT} -j MASQUERADE
  		;;
  	down)
  		iptables  -D FORWARD -i ${WGINT} -o ${OUTINT} -j ACCEPT
  		ip6tables -D FORWARD -i ${WGINT} -o ${OUTINT} -j ACCEPT
  		iptables  -t nat -D POSTROUTING -o ${OUTINT} -j MASQUERADE
  		ip6tables -t nat -D POSTROUTING -o ${OUTINT} -j MASQUERADE
  		;;
  	*)
  		echo $"Usage: $0 {up|down} <INTERACE>"
  		exit 1
  esac

• Allow forwarding:

  echo "net.ipv4.ip_forward=1" >> /etc/sysctl.d/forward.conf
  sysctl -p /etc/sysctl.d/forward.conf

• Start interface:

  wg-quick up wg0

• Enable the interface at boot:

  systemctl enable wg-quick@wg0

• Generate client config:

  umask 077
  CLIENT=client1
  wg genkey | tee privatekey-${CLIENT} | wg pubkey > publickey-${CLIENT}
  
  cat >wg-${CLIENT}.conf <<EOF
  [Interface]
  PrivateKey = $(cat privatekey-${CLIENT})
  Address = 192.168.2.2/24
  DNS = 8.8.8.8
  
  [Peer]
  PublicKey = $(wg show wg0 public-key)
  Endpoint = $(ip -4 -o addr show dev enp1s0 | awk '{print $4}' | cut -d "/" -f1):$(awk '/ListenPort/ {print $3}' /etc/wireguard/wg0.conf)
  AllowedIPs = 0.0.0.0/0, ::/0
  EOF

• Generate a QR-code and scan it with your client:

  qrencode -t ansiutf8 < wg-client1.conf

• Add peer to server:

  wg set wg0 peer $(cat publickey-${CLIENT}) allowed-ips 192.168.2.2/32