In this post I want to give a quick rundown of the few steps required to use WireGuard as a VPN. My setup uses a Raspberry Pi running Arch Linux ARM as the main gateway into my home network. I’ll configure another peer such that it can connect to the Pi and thus other devices in my network. The setup is IPv4-only at the moment because my ISP sucks. Also you should have some prior knowledge in networking.
As ArchLinux ARM (in its default configuration) ships with a Linux kernel with WireGuard support enabled, the first step is to install WireGuard’s userland tools.
$ pacman -S wireguard-tools
Naturally the package is not called
wireguard-tools on every platform. A
complete list of packages for different operating systems can be found
here. This gives you access to the
utility, which can perform several management tasks and the
which can load and apply configurations from files. I’ll not be making much use
of in-place configuration and instead jump directly into writing configuration
files, as they are pretty straightforward regardless. All configuration files
/etc/wireguard. They could be located anywhere but this path allows
shorthand notation in
First let’s set up the server (i.e. the Raspberry Pi), which the client can
then connect with in order to have a tunneled connection into my home network.
Create a configuration file in
wg0.conf. Set its
0600 because it will contain a private key and therefore shouldn’t be
world-readable. The configuration syntax is somewhat similar to Windows’ INI
files. The server’s interface is configured like this:
[Interface] Address = 192.168.42.1/24 ListenPort = 50040 PrivateKey = RG9udCB1c2UgdGhpcyB2YWx1ZSB5b3UgZHVtYmFzcyE= MTU = 1420
Address refers to the server’s address within the WireGuard tunnel. In my
setup I wanted to have the WireGuard “network” live under the netmask
192.168.42.0/24. Having the main gateway be
192.168.42.1 makes things
simple to understand.
50040 but can be anything of course
(I’m not even sure there is a definite default yet). Setting
the default and should work pretty much everywhere. Most interesting is the
PrivateKey field. WireGuard uses Ed25519 keys for authentication and this is
simply the server’s identity. The value can be generated via
And that’s is on the server side for now. You can call
wg-quick up wg0 to
enable this interface right now and verify its existence via the output of
ip link and
ip address commands.
Now for the same on the client.
[Interface] Address = 192.168.42.2/24 ListenPort = 50041 PrivateKey = TmV2ZXIgZXZlciBjb3B5IGtleXMgZnJvbSBndWlkZXM= MTU = 1420
No surprises here. The client also has a private key and its IP is to be
ListenPort should be different to the server’s port, as
WireGuard should be able to establish connections in both directions.
Now we’ll connect client and server. To make this work we’ll need to exchange
keys, as the server needs to know the client’s public key and vice versa. The
wg pubkey can be used to derive the public key from the private key.
For example, to get the server’s public key:
$ echo "RG9udCB1c2UgdGhpcyB2YWx1ZSB5b3UgZHVtYmFzcyE=" | wg pubkey QXJlIHlvdSByZWFkaW5nIHRoaXM/IEZvciByZWFsPyA=
(Sidenote: This will write the private key into your shell history. So you may
want to write the key into a file instead and
cat it’s contents into
While not strictly required, you may also generate and exchange a pre-shared
key between the peers, such that you also benefit from a layer of symmetric
cryptography in case you want to harden against quantum cryptanalysis. Such
a key can be generated via
$ wg genpsk eW91IGNvdWxkIGFjdHVhbGx5IHVzZSB0aGlzIG9uZSA=
Both the client’s and the server’s configuration needs an additional
For the server this section needs to look like this:
[Peer] PublicKey = a2V5c21hc2hrZXlzbWFzaGtleXNtYXNoa2V5c21hc2g= PresharedKey = eW91IGNvdWxkIGFjdHVhbGx5IHVzZSB0aGlzIG9uZSA= AllowedIPs = 192.168.42.2/32
And for the client like this:
[Peer] PublicKey = QXJlIHlvdSByZWFkaW5nIHRoaXM/IEZvciByZWFsPyA= PresharedKey = eW91IGNvdWxkIGFjdHVhbGx5IHVzZSB0aGlzIG9uZSA= AllowedIPs = 192.168.42.1/32 Endpoint = vpn-host.example:50040
Notice the additional
Endpoint value in the client. This is because the
client obviously needs to know where the server is located such that a
WireGuard tunnel can be established. This does not need to be a domain name and
could instead just be a raw IP address. Of course, in a VPN setup there is no
way we could know an
Endpoint value for the client. The server will learn the
client’s endpoint after each handshake, which is implicitly performed whenever
the client starts to send data to the server.
…aaand that’s it! Do
wg-quick up wg0 on both devices and try to perform a
ping over the WireGuard tunnel. You can inspect the state of the tunnel via:
Our devices can now talk to each other over WireGuard. But that is not
enough, as the aim is to allow routing traffic into my home network. I don’t
care about routing connections to the internet over WireGuard and simply want
my client to be able to access devices on the
192.168.0.0/24 network (i.e. my
We’re way more than halfway there. The last two puzzle pieces are: IP
forwarding, routing and having traffic from the client to
On Linux, routing can be enabled through
$ sysctl -w net.ipv4.ip_forward=1
To make this setting stick at boot, write this setting into a file in the
$ echo "net.ipv4.ip_forward=1" > /etc/sysctl.d/ip-forwarding.conf
Routing, or to be more precise masquerading, can be enabled via
$ iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
eth0 needs to be replaced with the canonical name of your server’s network
This can also be automated via WireGuard’s configuration manager, which is able
to execute commands when an interface is enabled and disabled. Add the command
PostUp option in the
[Interface] (...) PostUp = iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE PostDown = iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
PostDown removes this when the WireGuard interface is disabled.
Traffic to 192.168.0.0/24
This is added to the client’s configuration. Remember the
AllowedIPs key in
[Peer] section? You can simply add the whole network like this:
[Peer] (...) AllowedIPs = 192.168.42.1/32, 192.168.0.0/24
wg-quick will set up the routes accordingly.
That’s it. You’re done. Enjoy your VPN :)
This is a small update after a few months of very successfully using WireGuard.
You might find yourself in the following situation: Consider that you have two
devices, A and B, on your network. A has the address
B has the address
192.168.42.3. Your router and gateway is at
wg-quick sets routing up for you, simply sending all traffic
192.168.42.0/24 over your router. Sure you could configure a direct
connection between each and every peer manually, but this would get super
annoying super fast.
Device A might be… whatever. And device B might be some gizmo that you only boot up sporadically via Wake-on-LAN. You’ll find that, once B is booted up, A has no idea how to talk to B. The router doesn’t know that B is awake yet. And B never had any reason to communicate with the router. So the router won’t have any clue how to route A’s traffic to B. Remember how WireGuard is advertised as not being a talky protocol by default? This is exactly that principle in action and in most cases its perfectly fine. However here it falls flat on its face. What we need to do here, is make sure that the router always knows how to talk to B and that it maintains a route.
For this end, we can simply add the following line to B’s
[Peer] (...) PersistentKeepalive = 30
Now B will say “hello” to the router every 30 seconds, thus allowing the router to know of B’s existence. You can, of course, also choose a higher interval. Most important is the initial handshake from B to the router right after B has finished booting up.
And this concludes one of the few cases in which you should add
PersistentKeepalive to your WireGuard configurations. Seriously, if you
don’t encounter any issues just leave it out.