Posted in VPN

5:29 am, April 8, 2020

Getting Started with WireGuard » Miguel Mota | Software Developer

WireGuard ^[1] is a relatively new VPN tunnel protocol that aims to be very fast and easy to setup. It follows the Unix Philosophy ^[2] closely in that it only does one thing (creating secured VPN tunnels) and does it well.

If you’ve ever set up an VPN service such as OpenVPN ^[3] before then you know that it can get complicated because of all the steps you have to go through such as generating certificate authorities, issuing server and client keys and certificates, setting up multiple configuration files, configuring firewall rules, setting up route traffic forwarding, etc. which can either be dreadful or daunting. WireGuard is changing all that by simplifying the process of getting up and running in no time and allowing for easy configuration to connect multiple clients (peers).

Why use WireGuard?

A VPN helps protect you from man in the middle attacks.
Protect your privacy against ISPs that snoop into your traffic.
Get around internet censorship in countries.

Advantages of WireGuard over other VPNs:

It’s kernel-based; improved performance.
Establishes connections in less than 100ms.
Small footprint; can be ran in virtually any device, ie. embedded devices.
Easy to configure and deploy as SSH; reduces attack surface since there’s less complexity.
Uses modern and improved cryptographic standards ^[4].
Simple handshake occurring every few minutes to ensure connection secrecy.
IP roaming support meaning you can change wifi networks or disconnect from wifi or celluar and the VPN tunnel connection won’t be lost. It just works!

What we’ll be going over

This post assumes that you’ve never installed a VPN service before and we’ll be using an Ubuntu machine since it’s the most popular distro.

This post is pretty verbose! but you can skip to the TLDR;^[5] to see the final scripts and configuration files used if you’re familiar with the concepts already.

The steps outlined in this post are:

Setting up a server ^[6]
Installing WireGuard on server ^[7]
Generating server keys ^[8]
Creating server configuration file ^[9]
Enabling IP forwarding on server ^[10]
Installing WireGuard on client ^[11]
Generating client keys ^[12]
Creating client configuration file ^[13]
Setting client info on server config ^[14]
Starting WireGuard service on server ^[15]
Starting WireGuard service on client ^[16]
Connecting a mobile client to server ^[17]

Please note that in WireGuard land there is no “server” and “client” in the traditional sense. Rather, computers and devices connected to each other are known as “peers”. For simplicity sake, we’ll be using “server” to mean the hosted server that will be forwarding all our traffic to, and we’ll be using “client” to refer to the home computer that forwards all it’s traffic to the server.

Setting up a server

I’ll be using a free tier EC2 micro instance from AWS for the example (and tearing down it afterwards). If you have an AWS account you can launch a new instance by going to:

EC2 → Launch Instance → t2.micro with Ubuntu → Review and Launch → Launch

In this example I’m running Ubuntu 18.04 (Bionic Beaver).

Installing WireGuard on server

To install wireguard on Ubuntu <19.04 run the following comands:

sudo add-apt-repository ppa:wireguard/wireguard
sudo apt-get update
sudo apt-get install wireguard

If your server is using a different distro then look at the WireGuard installation instructions ^[18].

ubuntu@ip-172-30-0-233:~$ sudo add-apt-repository ppa:wireguard/wireguard
 WireGuard is a novel VPN that runs inside the Linux Kernel. This is the Ubuntu packaging for WireGuard. More info may be found at its website, listed below.

More info: https://www.wireguard.com/
Packages: wireguard wireguard-tools wireguard-dkms

Install with: $ apt install wireguard
 More info: https://launchpad.net/~wireguard/+archive/ubuntu/wireguard
Press [ENTER] to continue or Ctrl-c to cancel adding it.

<truncated>

Fetched 18.5 MB in 4s (4840 kB/s)

ubuntu@ip-172-30-0-233:~$ sudo apt-get update
Hit:1 http://us-east-1.ec2.archive.ubuntu.com/ubuntu bionic InRelease
Hit:2 http://us-east-1.ec2.archive.ubuntu.com/ubuntu bionic-updates InRelease
Hit:3 http://us-east-1.ec2.archive.ubuntu.com/ubuntu bionic-backports InRelease
Hit:4 http://security.ubuntu.com/ubuntu bionic-security InRelease
Hit:5 http://ppa.launchpad.net/wireguard/wireguard/ubuntu bionic InRelease
Reading package lists... Done

ubuntu@ip-172-30-0-233:~$ sudo apt-get install wireguard
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:

<truncated>

update-alternatives: using /usr/bin/g++ to provide /usr/bin/c++ (c++) in auto mode
Setting up build-essential (12.4ubuntu1) ...
Setting up wireguard-dkms (1.0.20200401-1ubuntu1~18.04) ...
Loading new wireguard-1.0.20200401 DKMS files...
Building for 4.15.0-1057-aws
Building initial module for 4.15.0-1057-aws
Done.

wireguard:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/4.15.0-1057-aws/updates/dkms/

depmod...

DKMS: install completed.
Setting up wireguard (1.0.20200319-0ppa1~18.04) ...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
Processing triggers for man-db (2.8.3-2ubuntu0.1) ...

Let’s launch a shell as root with sudo -s to avoid having to type sudo every time from now on:

ubuntu@ip-172-30-0-233:~$ sudo -s
root@ip-172-30-0-233:~#

Run wg to check if installation was successful which should not output anything if everything is OK:

root@ip-172-30-0-233:/etc/wireguard/keys# wg
root@ip-172-30-0-233:/etc/wireguard/keys#

The two WireGuard commands we’ll be using are:

wg for configuring WireGuard interfaces.
wg-quick for starting and stopping WireGuard VPN tunnels.

Generating server keys

WireGuard configuration files will live under /etc/wireguard/ so let’s create a directory named keys there to store the keys we’ll generate:

root@ip-172-30-0-233:~# mkdir /etc/wireguard/keys

Go into the /etc/wireguard/keys/ directory:

root@ip-172-30-0-233:~# cd /etc/wireguard/keys

Set the directory user mask to 077 by running umask 077. A umask of 077 allows read, write, and execute permissions for the file’s owner (root in this case), but prohibits read, write, and execute permissions for everyone else and makes sure credentials don’t leak in a race condition:

root@ip-172-30-0-233:/etc/wireguard/keys# umask 077

WireGuard uses asymmetric public/private Curve25519 key pairs for authentication between client and server.

Use the wg genkey command to generate a private key. We can generate both the private and public key at once by piping the private key output to tee to save it to file but also to forward the private key to wg publickey which derived the public key from a private key and the save it to a file.

So the command to run is wg genkey | tee privatekey | wg pubkey > publickey to generate the key pair at once:

root@ip-172-30-0-233:/etc/wireguard/keys# wg genkey | tee privatekey | wg pubkey > publickey

If we do an ls we see there’s a privatekey and publickey file:

root@ip-172-30-0-233:/etc/wireguard/keys# ls
privatekey  publickey

Outputting the contents of the private key file shows us the random key it generated in base64 format:

root@ip-172-30-0-233:/etc/wireguard/keys# cat privatekey
wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=

Likewise the public key it derived from the private key is in base64 format:

root@ip-172-30-0-233:/etc/wireguard/keys# cat publickey
H6StMJOYIjfqhDvG9v46DSX9UlQl52hOoUm7F3COxC4=

We’ll be needing the private key for the WireGuard server configuration, and the public key for the client configuration.

Creating server configuration file

Go into the /etc/wireguard/ directory and create a new file wg0.conf. WireGuard will create a new network interface named the same as the filename so it’s common convention to denote the first WireGuard network interface as wg0 for context:

root@ip-172-30-0-233:/etc/wireguard# touch /etc/wireguard/wg0.conf

Open up the server configuration file /etc/wireguard/wg0.conf in your favorite editor:

root@ip-172-30-0-233:/etc/wireguard# vim /etc/wireguard/wg0.conf

Paste the following configuration into the new config file:

[Interface]
PrivateKey = <server private key>
Address = 10.0.0.1/24
ListenPort = 51820

The config files are in standard INI ^[19] format.

Replace the PrivateKey value with the private key content you generated earlier:

[Interface]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
Address = 10.0.0.1/24
ListenPort = 51820

The address 10.0.0.1 was chosen because it’s an available private subnet on the server. If your server is using that IP range already, then pick a different address like 192.168.2.1 to avoid conflicts.

The [Interface] section is for configuration the new WireGuard interface we are creating.

PrivateKey is your server’s private key.
Address is the private network IP address range that we’re assigning to for this network interface.
ListenPort is the host port to run the service on. This port will need to be publicly accessible. The port 51820 is the default port.

Make sure to enable the port 51820 for UDP traffic. If using EC2 then you should allow it under the Security Group for the EC2 instance.

EC2 instance → Security groups → Click on security group → Edit inbound rules → Add rules → Custom UDP → Port range: 51820 → Source: Anywhere → Save rules

The rules immediately take effect.

If your server is behind a NAT (which in our case it is because it’s on EC2 behind a VPC) then all traffic needs to be forwarded from the default interface to the WireGuard interface.

To find out the name of the default interface run ip route:

root@ip-172-30-0-233:/etc/wireguard/keys# ip route | grep default | awk '{print $5}'
eth0

Now add forwarding rules for forwarding in the server configuration file using the PostUp and PostDown config settings where PostUp value command is ran when the WireGuard service starts and PostDown value command runs when the service is shutting down.

[Interface]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
Address = 10.0.0.1/24
ListenPort = 51820
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

The three iptable rules are:

iptables -A FORWARD -i %i -j ACCEPT for allowing inbound traffic received by the interface.
iptables -A FORWARD -o %i -j ACCEPT for allowing outbound traffic from the interface.
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE for masking the private IP address of the interface with the external IP address of the default interface.

Enabling IP forwarding on server

By default IP forwarding is disabled meaning that if the interface receives a packet that wasn’t intended for it then it’ll reject it. Since we need to pass on packets from one interface to another then we need to allow IP forwarding.

Open up the file /etc/sysctl.conf for editing:

root@ip-172-30-0-233:/etc/wireguard# vim /etc/sysctl.conf

Allow forwarding of IP packets by uncommenting out the line net.ipv4.ip_forward=1 near line 28:

# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1

Run sysctl -p for the changes to take effect without requiring a reboot:

root@ip-172-30-0-233:/etc/wireguard# sysctl -p
net.ipv4.ip_forward = 1

Confirm that IP forwarding is enabled by outputting the contents of /proc/sys/net/ipv4/ip_forward which should return 1:

root@ip-172-30-0-233:/etc/wireguard# cat /proc/sys/net/ipv4/ip_forward
1

The server is almost fully configured. It’s only now missing information about the client so let’s set up the client next.

Installing WireGuard on client

Jump back to your client machine and install WireGuard. My client machine is running Arch linux but the process will be the same for most linux distros. If you’re running Ubuntu on the client then do the same install steps you did on the server above or look at the official WireGuard installation instructions ^[20].

Ubuntu WireGuard install instructions:

$ sudo add-apt-repository ppa:wireguard/wireguard
$ sudo apt-get update
$ sudo apt-get install wireguard

If running Arch like I am, then these are the WireGuard install instructions:

$ sudo pacman -S wireguard-tools wireguard-dkms

Let’s launch a shell as root with sudo -s to avoid having to type sudo every time from now on:

$ sudo -s
[root@archlinux ~]#

Generating client keys

The process of generating WireGuard keys on the client is the same as how it’s done on the server. Create the directory /etc/wireguard/keys and set the user mask to 077.

[root@archlinux ~]# mkdir /etc/wireguard/keys
[root@archlinux ~]# cd /etc/wireguard/keys
[root@archlinux keys]# umask 077

Generate a private and public key pair for the client using the same command as we did on the server:

[root@archlinux keys]# wg genkey | tee privatekey | wg pubkey > publickey

Output the key contents which we’ll be needing soon in our configuration files:

[root@archlinux keys]# cat privatekey
cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=
[root@archlinux keys]# cat publickey
vi4TCAo8TNRkpf4ZpiMsp3YHaOLrcouSDkrm4wJxezw=

Creating client configuration file

On the client create the configuration /etc/wireguard/wg0.conf:

[root@archlinux keys]# vim /etc/wireguard/wg0.conf

Paste the configuration into your client configuration file:

[Interface]
Address = 10.0.0.2/32
PrivateKey = <client private key>

Replace the PrivateKey value with your client’s private key:

[Interface]
Address = 10.0.0.2/32
PrivateKey = cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=

Set the DNS to Cloudflare’s public DNS resolver 1.1.1.1 which is fast and secure:

[Interface]
Address = 10.0.0.2/32
PrivateKey = cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=
DNS = 1.1.1.1

The [Interface] section is for configuration the new WireGuard interface we are creating.

Address is the private network IP address range that we’re assigning to for this network interface.
PrivateKey is your client’s private key.
DNS is the DNS resolve to use.

Setting server peer on client config

The next step is to set information about the server in the client configuration file under the [Peer] section:

[Interface]
Address = 10.0.0.2/32
PrivateKey = cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=
DNS = 1.1.1.1

[Peer]
PublicKey = <server public key>
Endpoint = <server public ip>:51820
AllowedIPs = 0.0.0.0/0

Replace the PublicKey value to your server’s public key and set the Endpoint to be your server’s public IP address:

[Interface]
Address = 10.0.0.2/32
PrivateKey = cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=
DNS = 1.1.1.1

[Peer]
PublicKey = H6StMJOYIjfqhDvG9v46DSX9UlQl52hOoUm7F3COxC4=
Endpoint = 54.225.123.18:51820
AllowedIPs = 0.0.0.0/0

Because our server is behind a NAT, we’ll also need to set PersistentKeepalive to keep the connection alive:

[Interface]
Address = 10.0.0.2/32
PrivateKey = cAqmevIKScn5l4Jg1F69KEIty6gVb8wGNqNlApvzc0c=
DNS = 1.1.1.1

[Peer]
PublicKey = H6StMJOYIjfqhDvG9v46DSX9UlQl52hOoUm7F3COxC4=
Endpoint = 54.225.123.18:51820
AllowedIPs = 0.0.0.0/0
PersistentKeepalive = 25

The [Peer] section is for configuration information about the peer it’s connecting to, which in this case it’s the client connection to the server.

PublicKey is the public key of the server.
Endpoint is your server’s public IP and port the server’s interface is listening, configured with ListenPort in the server’s config.
AllowedIPs is the IP range to allow forwarding from. Setting it to 0.0.0.0/0 will forward all traffic over the tunnel.
PersistentKeepalive is the interval to periodically send keepalive packets to the server.

If you’re not sure what your server’s public address is, you can do an IP lookup by doing a DNS query request to myip.opendns.com:

root@ip-172-30-0-233:/etc/wireguard# dig +short myip.opendns.com @resolver1.opendns.com
54.225.123.18

If your server is an EC2 instance, you get query the metadata endpoint to get the public IP address:

root@ip-172-30-0-233:/etc/wireguard# curl http://169.254.169.254/latest/meta-data/public-ipv4
54.225.123.18

Setting client peer on server config

Go back into the server and edit the config. We’re going to add information about the client so that the server and client can authenticate with each other.

root@ip-172-30-0-233:/etc/wireguard/keys# vim /etc/wireguard/wg0.conf

Add the [Peer] section to the server config:

[Interface]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
Address = 10.0.0.1/24
ListenPort = 51820
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

[Peer]
PublicKey = <client public key>
AllowedIPs = 10.0.0.2/32

Replace the PublicKey value with your client’s public key:

[Interface]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
Address = 10.0.0.1/24
ListenPort = 51820
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

[Peer]
PublicKey = vi4TCAo8TNRkpf4ZpiMsp3YHaOLrcouSDkrm4wJxezw=
AllowedIPs = 10.0.0.2/32

The [Peer] section is for configuration information about the peer it’s connecting to, which in this case it’s the servers connection to the client.

PublicKey is the client’s public key.
AllowedIPs are allowed client IP addresses.

Starting WireGuard service on server

Now that the server has the client peer information we can start the WireGuard service with wg-quick up wg0 on the server:

root@ip-172-30-0-233:/etc/wireguard/keys# wg-quick up wg0
[#] ip link add wg0 type wireguard
[#] wg setconf wg0 /dev/fd/63
[#] ip -4 address add 10.0.0.1/24 dev wg0
[#] ip link set mtu 8921 up dev wg0
[#] iptables -A FORWARD -i wg0 -j ACCEPT; iptables -A FORWARD -o wg0 -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

Depending on your Ubuntu installation, you might need to install additional kernel modules. If you got the error “RNETLINK answers: Operation not supported” trying to start the wg0 interface then install the following packages on the server:

root@ip-172-30-0-233:/etc/wireguard# apt-get install wireguard-dkms wireguard-tools linux-headers-$(uname -r)

To start WireGuard across reboots you’ll need to enable the service to add it to the systemd init system by running systemctl enable wg-quick@wg0.service:

root@ip-172-30-0-233:/etc/wireguard/keys# systemctl enable wg-quick@wg0.service
Created symlink /etc/systemd/system/multi-user.target.wants/wg-quick@wg0.service → /lib/systemd/system/wg-quick@.service.

Check the status by running systemctl status wg-quick@wg0.service and if you see Active: active (exited) then if everything is good so far:

root@ip-172-30-0-233:/etc/wireguard/keys# systemctl status wg-quick@wg0.service
● wg-quick@wg0.service - WireGuard via wg-quick(8) for wg0
   Loaded: loaded (/lib/systemd/system/wg-quick@.service; indirect; vendor preset: enabled)
   Active: active (exited) since Thu 2020-04-02 06:35:22 UTC; 1s ago
     Docs: man:wg-quick(8)
           man:wg(8)
           https://www.wireguard.com/
           https://www.wireguard.com/quickstart/
           https://git.zx2c4.com/wireguard-tools/about/src/man/wg-quick.8
           https://git.zx2c4.com/wireguard-tools/about/src/man/wg.8
  Process: 10730 ExecStart=/usr/bin/wg-quick up wg0 (code=exited, status=0/SUCCESS)
 Main PID: 10730 (code=exited, status=0/SUCCESS)

Apr 02 06:35:21 ip-172-30-0-233 systemd[1]: Starting WireGuard via wg-quick(8) for wg0...
Apr 02 06:35:22 ip-172-30-0-233 wg-quick[10730]: [#] ip link add wg0 type wireguard
Apr 02 06:35:22 ip-172-30-0-233 wg-quick[10730]: [#] wg setconf wg0 /dev/fd/63
Apr 02 06:35:22 ip-172-30-0-233 wg-quick[10730]: [#] ip -4 address add 10.0.0.1/24 dev wg0
Apr 02 06:35:22 ip-172-30-0-233 wg-quick[10730]: [#] ip link set mtu 8921 up dev wg0
Apr 02 06:35:22 ip-172-30-0-233 wg-quick[10730]: [#] iptables -A FORWARD -i wg0 -j ACCEPT; iptables -A FORWARD -o wg0 -j ACCEPT; ipt
Apr 02 06:35:22 ip-172-30-0-233 systemd[1]: Started WireGuard via wg-quick(8) for wg0.

Verify that new iproute rules have been applied with iptables -L -n:

root@ip-172-30-0-233:/etc/wireguard# iptables -L -n
Chain INPUT (policy ACCEPT)
target     prot opt source               destination

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0
ACCEPT     all  --  0.0.0.0/0            0.0.0.0/0

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

Running the command ifconfig shows the new network interface wg0 with the internal IP address we specified 10.0.0.1:

root@ip-172-30-0-233:/etc/wireguard# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 9001
        inet 172.30.0.233  netmask 255.255.255.0  broadcast 172.30.0.255
        inet6 fe80::1097:5bff:fe30:d57  prefixlen 64  scopeid 0x20<link>
        ether 12:97:5b:30:0d:57  txqueuelen 1000  (Ethernet)
        RX packets 1151269  bytes 524679242 (524.6 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 1022229  bytes 345390292 (345.3 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 526  bytes 48787 (48.7 KB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 526  bytes 48787 (48.7 KB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

wg0: flags=209<UP,POINTOPOINT,RUNNING,NOARP>  mtu 8921
        inet 10.0.0.1  netmask 255.255.255.0  destination 10.0.0.1
        unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Starting WireGuard service on client

First take note of your current public IP address on the client machine:

[root@archlinux wireguard]# dig +short myip.opendns.com @resolver1.opendns.com
65.88.88.4

After we start the WireGuard service on the client then the public IP address will be resolved to the server’s public IP address.

Start the WireGuard service using wg-quick just like we did previously on the server:

[root@archlinux wireguard]# wg-quick up wg0

Now that WireGuard is running, check the public IP address again of the client and it should now be the public IP address of the server:

[root@archlinux wireguard]# dig +short myip.opendns.com @resolver1.opendns.com
54.225.123.18

Success! WireGuard is correctly configured and the peers are connected.

Connecting a mobile client to server

Download the WireGuard app for iOS ^[21] or Android ^[22] on your device.

For this example we’ll create a second client (an iPhone) to connect to the WireGuard server. The same steps will need to be followed from when we setup the first client.

We can generate keys directly on the device and set up the configuration manually but that’s not quick and ideal. Instead we can generate the keys and configuration on the server and then securely transfer the information into the WireGuard app.

Run wg genkey but specify different filenames this time to distinguish them from the server keys:

root@ip-172-30-0-233:/etc/wireguard# cd /etc/wireguard/keys
root@ip-172-30-0-233:/etc/wireguard/keys# wg genkey | tee iphone_privatekey | wg pubkey > iphone_publickey
root@ip-172-30-0-233:/etc/wireguard/keys# cat iphone_privatekey
kFnMqMSiAluwb/xWgemXhjLh/II/sb92OoYCbh7yaWw=
root@ip-172-30-0-233:/etc/wireguard/keys# cat iphone_publickey
cKIxzfp5ESpdM34vT2Qk/S7yvprOff6Le4YnyOTI4B8=

Open up the server config /etc/wireguard/wg0.conf in your favorite editor:

root@ip-172-30-0-233:/etc/wireguard/keys# vim /etc/wireguard/wg0.conf

Add the second peer section and include the client’s public key and IP address:

[Interface]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
Address = 10.0.0.1/24
ListenPort = 51820
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

[Peer]
PrivateKey = wIObajifv6U2emcZsAGNZbbWzkyrs84EEyr+bgmlB3M=
AllowedIPs = 10.0.0.2/32

[Peer]
PublicKey = cKIxzfp5ESpdM34vT2Qk/S7yvprOff6Le4YnyOTI4B8=
AllowedIPs = 10.0.0.3/32

Create a new configuration file for the iPhone client on the server. We’ll name it wgo-iphone.conf:

root@ip-172-30-0-233:/etc/wireguard/keys# vim /etc/wireguard/wg0-iphone.conf

Paste client configuration but remember to use a different private IP that differs from the first client.

[Interface]
PrivateKey = kFnMqMSiAluwb/xWgemXhjLh/II/sb92OoYCbh7yaWw=
Address = 10.0.0.3/32
DNS = 1.1.1.1

[Peer]
PublicKey = H6StMJOYIjfqhDvG9v46DSX9UlQl52hOoUm7F3COxC4=
Endpoint = 54.225.123.18:51820
AllowedIPs = 0.0.0.0/0
PersistentKeepalive = 25

Install qrencode ^[23] on the server to generate a QRCode from the configuration file.

You’ll be scanning this qrcode in the WireGuard app to download the configuration. This is a safer way to transport credentials since the keys and configuration files don’t need to be zipped and moved.

Generate the text based qrcode image in your terminal with qrencode -t ansiutf8 < wg0-iphone.conf

root@ip-172-30-0-233:/etc/wireguard# qrencode -t ansiutf8 < wg0-iphone.conf
<qrcode image>

In the WireGuard app go to: Add a tunnel → Create from QRCode

Scan the qrcode code generated in the terminal and make sure to Allow the VPN configuration in the settings popup.

Enable the VPN by toggling on the switch.

Visit ipchicken.com ^[24] in the browser to verify the public iP address has changed.

Generating vanity addresses

It’s easy to lose track of which keys belong to which devices since they all look like random strings. To make it easier to associate keys to devices you can use this vanity address generator ^[25] to generate public keys that contain a custom array of characters.

For example, we’ll generate a key pair where the public key starts with “iPho” to denote that it’s a key pair to be used on the iPhone client.

First install the vanity address generator with cargo ^[26]:

$ cargo install wireguard-vanity-address

Now just specify the list of characters that you want in the public key base64 output:

$ wireguard-vanity-address ipho
searching for 'ipho' in pubkey[0..10], one of every 149796 keys should match
one trial takes 83.6 us, CPU cores available: 8
est yield: 1.6 seconds per key, 638.83e-3 keys/s
hit Ctrl-C to stop
private YPpudjAoVCnaPUJdcEVhj5Ttedq7WP1ozL+ZdtuTC1g=  public cHklbipHoMS9CA8XlRdKMBOOIfQC28Ut8SVyYsqmox0=
private kD6FSIZehv1DKJ28MKJQcmSDdd69U3s4s11ymtP1Ekc=  public iPHoaaQye7+OJNq/TfOvXjMr99pq9ADDDlGynRQ6KQ8=
private aEJ33LXCeipouhiAoQjfMjtwrHPfZDvKLguE8XlawnY=  public iPHoEoUy4WgkUXr4e47IkA06IZqVI/AqHNS2RZlGhHM=
^C

It’ll keep generating until you manually stop it when you see a key pair that you like.

Automation

A nice tool to automate the process of setting up a WireGuard VPN is Algo ^[27].

Algo is a set of Ansible ^[28] scripts to help you set up and configure WireGuard on the remote server from your local machine.

To get started, clone the algo repository and install the python dependencies:

~$ git clone https://github.com/trailofbits/algo.git
~$ cd algo/
~/algo$ pip install virtualenv
~/algo$ python3 -m virtualenv --python="$(command -v python3)" .env && source .env/bin/activate && python3 -m pip install -U pip virtualenv && python3 -m pip install -r requirements.txt

Now run the algo executable file to start the walkthough of deploying an Algo server to the cloud:

(.env) ~/algo$ ./algo
[Cloud prompt]
What provider would you like to use?
    1. DigitalOcean
    2. Amazon Lightsail
    3. Amazon EC2
    4. Microsoft Azure
    5. Google Compute Engine
    6. Hetzner Cloud
    7. Vultr
    8. Scaleway
    9. OpenStack (DreamCompute optimised)
    10. CloudStack (Exoscale optimised)
    11. Install to existing Ubuntu 18.04 or 19.10 server (for more advanced users)

Enter the number of your desired provider
:
<truncated>

TLDR;

Here’s a summary of the server and client configuration and commands used in this post:

Server

Server commands:

sudo -s
apt-get install wireguard
mkdir -p /etc/wireguard/keys
cd /etc/wireguard/keys
umask 077
wg genkey | tee privatekey | wg pubkey > publickey
vim /etc/wireguard/wg0.conf # see server config below
vim /etc/sysctl.conf # uncomment line "net.ipv4.ip_forward=1"
sysctl -p
wg-quick up wg0
systemctl enable wg-quick@wg0.service

Server config /etc/wireguard/wg0.conf:

[Interface]
PrivateKey = <server private key>
Address = 10.0.0.1/24
ListenPort = 51820
PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -A FORWARD -o %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -D FORWARD -o %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE

[Peer]
PublicKey = <client public key>
AllowedIPs = 10.0.0.2/32

Client

Client commands:

sudo -s
apt-get install wireguard
mkdir -p /etc/wireguard/keys
cd /etc/wireguard/keys
umask 077
wg genkey | tee privatekey | wg pubkey > publickey
vim /etc/wireguard/wg0.conf # see client config below
wg-quick up wg0

Client config /etc/wireguard/wg0.conf:

[Interface]
PrivateKey = <client private key>
Address = 10.0.0.2/32
DNS = 1.1.1.1

[Peer]
PublicKey = <server public key>
Endpoint = <server public ip>:51820
AllowedIPs = 0.0.0.0/0
PersistentKeepalive = 25

Resources

Follow discussion on Hacker News ^[29].

References

^{^} WireGuard (www.wireguard.com)
^{^} Unix Philosophy (homepage.cs.uri.edu)
^{^} OpenVPN (github.com)
^{^} cryptographic standards (en.wikipedia.org)
^{^} TLDR;
^{^} Setting up a server
^{^} Installing WireGuard on server
^{^} Generating server keys
^{^} Creating server configuration file
^{^} Enabling IP forwarding on server
^{^} Installing WireGuard on client
^{^} Generating client keys
^{^} Creating client configuration file
^{^} Setting client info on server config
^{^} Starting WireGuard service on server
^{^} Starting WireGuard service on client
^{^} Connecting a mobile client to server
^{^} installation instructions (www.wireguard.com)
^{^} INI (en.wikipedia.org)
^{^} installation instructions (www.wireguard.com)
^{^} iOS (apps.apple.com)
^{^} Android (play.google.com)
^{^} qrencode (github.com)
^{^} ipchicken.com (ipchicken.com)
^{^} vanity address generator (github.com)
^{^} cargo (crates.io)
^{^} Algo (github.com)
^{^} Ansible (github.com)
^{^} Hacker News (news.ycombinator.com)

keywords miguel mota,web developer,software developer,html5 developer,javascript developer,blockchain developer

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