Document how to use WireGuard on Ubuntu clients (#1071)

README.md

@@ -190,6 +190,7 @@ After this process completes, the Algo VPN server will contains only the users l
 * Client setup
   - Setup [Android](docs/client-android.md) clients
   - Setup [Generic/Linux](docs/client-linux.md) clients with Ansible
+  - Setup Ubuntu clients to use [WireGuard](docs/client-linux-wireguard.md)
 * Cloud setup
   - Configure [Amazon EC2](docs/cloud-amazon-ec2.md)
   - Configure [Azure](docs/cloud-azure.md)

docs/client-linux-wireguard.md

@@ -0,0 +1,48 @@
+# Using Ubuntu Server as a Client with WireGuard
+
+## Install WireGuard
+
+To connect to your Algo VPN using [WireGuard](https://www.wireguard.com) from an Ubuntu Server 16.04 (Xenial) or 18.04 (Bionic) client, first install WireGuard on the client:
+
+```
+# Add the WireGuard repository:
+sudo add-apt-repository ppa:wireguard/wireguard
+# Update the list of available packages (not necessary on Bionic):
+sudo apt update 
+# Install the tools and kernel module:
+sudo apt install wireguard
+```
+
+(For installation on other Linux distributions, see the [Installation](https://www.wireguard.com/install/) page on the WireGuard site.)
+
+## Locate the Config File
+
+The Algo-generated config files for WireGuard are named `configs/<ip_address>/wireguard/<username>.conf` on the system where you ran `./algo`. One file was generated for each of the users you added to `config.cfg` before you ran `./algo`. Each Linux and Android client you connect to your Algo VPN must use a different WireGuard config file. Choose one of these files and copy it to your Linux client.
+
+If your client is running Bionic (or another Linux that uses `systemd-resolved` for DNS) you should first edit the config file. Comment out the line that begins with `DNS =` and replace it with:
+```
+PostUp = systemd-resolve -i %i --set-dns=172.16.0.1 --set-domain=~.
+```
+Use the IP address shown on the `DNS =` line (for most, this will be `172.16.0.1`). If the `DNS =` line contains multiple IP addresses, use multiple  `--set-dns=` options.
+
+## Configure WireGuard
+
+Finally, install the config file on your client as `/etc/wireguard/wg0.conf` and start WireGuard:
+
+```
+# Install the config file to the WireGuard configuration directory on your
+# Bionic or Xenial client:
+sudo install -o root -g root -m 600 <username>.conf /etc/wireguard/wg0.conf
+# Start the WireGuard VPN:
+sudo systemctl start wg-quick@wg0
+# Check that it started properly:
+sudo systemctl status wg-quick@wg0
+# Verify the connection to the Algo VPN:
+sudo wg
+# See that your client is using the IP address of your Algo VPN:
+curl ipv4.icanhazip.com
+# Optionally configure the connection to come up at boot time:
+sudo systemctl enable wg-quick@wg0
+```
+
+(If your Linux distribution does not use `systemd`, you can bring up WireGuard with `sudo wg-quick up wg0`).