+++
title = "Wireguard Gateway & Android"
date = 2019-07-07T14:41:00+02:00
author = "MH"
cover = ""
tags = ["VPN", "Wireguard", "Android", "Setup"]
description = "Setup a Linux Wireguard Gateway and connet with Android"
showFullContent = false
draft = false
+++

# Setup your Linux Server

Your Linux server should be accessible via a public IP by UDP.
If the IP address changes, use DynDNS.

First **install WireGuard** on your Linux server. On the official website you will find
the right way for your Linux distro:
[WireGuard.com/install](https://www.wireguard.com/install/)

Then **configure** the Gateway.
We will use the range 100.64.0.0/10 (RFC 6598) because it doesn't colide with private IPv4 adresses (RFC 1918).

    echo '[Interface]'                   > /etc/wireguard/wg0.conf
    echo "PrivateKey = $(wg genkey)"    >> /etc/wireguard/wg0.conf
    echo 'ListenPort = 50002'           >> /etc/wireguard/wg0.conf
    echo "Address = 100.64.0.1/10"      >> /etc/wireguard/wg0.conf

    iptables -t nat -A POSTROUTING -s 100.64.0.0/10 -o eth0 -j MASQUERADE
    systemctl enable --now wg-quick@wg0

Don't forget to save the iptables rules for the next start. The easiest way is to include this config in wg0.conf:
    PostUp = iptables -I FORWARD -i eth0 -j ACCEPT; iptables -I FORWARD -o eth0 -j ACCEPT; iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE
    PostDown = iptables -D FORWARD -i eth0 -j ACCEPT; iptables -D FORWARD -o eth0 -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

To get the public key (you need it later on):

    wg pubkey <<<$(grep PrivateKey /etc/wireguard/wg0.conf  | cut -d ' ' -f3)

Now the gateway is configured and running. To get some information, type in wg and use systemd:

    systemctl status wg-quick@wg0
    wg

Enable IP forwarding in the Linux kernel by uncommenting or adding (uncommenting) `net.ipv4.ip_forward = 1` in /etc/sysctl.conf to persist the setting between system restarts. Use sysctl -w net.ipv4.ip_forward=1 to enable IP forwarding immediately without having to reboot.

# Setup your Android

Download the App from [F-Droid](https://f-droid.org/en/packages/com.wireguard.android/) or [Google Play](https://play.google.com/store/apps/details?id=com.wireguard.android).

In WireGuard, you must manually set an IP address for each client. The ``100.64.0.0/10`` area has hosts from ```100.64.0.1``` to ```100.127.255.254```, the first one is already occupied by the gateway, so we use ```100.64.0.0.2```.

  ![]({{<siteurl>}}img/wireguard-android/A.jpg) |  ![]({{<siteurl>}}img/wireguard-android/B.jpg) |  ![]({{<siteurl>}}img/wireguard-android/C.jpg)
 -------|----------|--------
 Open the app and "Create from scratch" |  Generate a key pair. Make a note of the public key, you will need it later. Name the configuration and add the client IP address with 32 mask.  | Add a peer. Now enter the gateway information. Allowed IPs is ```0.0.0.0/0```.

# Add Android Client to Server

Now add the client information to the gateway and restart the interface.

    [Peer]                            >> /etc/wireguard/wg0.conf
    PublicKey = <Client-Pub-Key>      >> /etc/wireguard/wg0.conf
    AllowedIPs = 100.64.0.2/32      >> /etc/wireguard/wg0.conf

    systemctl restart wg-quick@wg0 && systemctl status wg-quick@wg0


# Sources
[Wireguard Quickstart](https://www.wireguard.com/quickstart/)

Heise [Besser tunneln](https://www.heise.de/select/ct/2019/5/1551091519824850)

Witepaper [WireGuard: Next Generation Kernel Network Tunnel](https://www.wireguard.com/papers/wireguard.pdf)

Demo Video [Test WireGuard VPN net roaming](https://video.obermui.de/videos/watch/5009724a-a670-4130-bc99-4ab820773da6)