Configure a Wireguard interface (wg)

WireGuard multiple platform vpn solution. WireGuard itself is now integrated into the linux kernel since v5.6. Only the userland configuration tools are required.

Installation

The most straightforward method to configure WireGuard is to use the tool wg-quick available in the package wireguard-tools-wg-quick.

Install the meta package wireguard-tools to install the necessary WireGuard packages and iptables as follows:

# apk add wireguard-tools iptables

Configuration

Create Server Keys and Interface Config

Create a server private and public key:

# wg genkey | tee server.privatekey | wg pubkey > server.publickey

Then, we create a new config file /etc/wireguard/wg0.conf using these new keys as follows:

Contents of /etc/wireguard/wg0.conf

[Interface] Address = 192.168.2.1/24 ListenPort = 45340 PrivateKey = <server private key value> # the key from the previously generated privatekey file PostUp = iptables -A FORWARD -i %i -j ACCEPT; iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE;iptables -A FORWARD -o %i -j ACCEPT PostDown = iptables -D FORWARD -i %i -j ACCEPT; iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE;iptables -D FORWARD -o %i -j ACCEPT [Peer] PublicKey = <client public key value> # obtained from client device via wireguard connection setup process AllowedIPs = 192.168.2.2/32

The PostUp and PostDown iptable rules forward traffic from the wg0 subnet (192.168.2.1/24) to the lan subnet on interface eth0. Refer to this WireGuard documentation for information on adding peers to the config file.

Bring up the new wg0 interface:

# wg-quick up wg0

To take it down, we can use wg-quick down wg0 which will clean up the interface and remove the iptables rules.

Note: If running in a Docker container, you will need to run with --cap-add=NET_ADMIN to modify your interfaces.

Use with network interfaces

To enable connecting with Wireguard on boot, open your /etc/network/interfaces and add this information after your auto other network interfaces as follows:

Contents of /etc/network/interfaces

... auto wg0 iface wg0 inet static pre-up wg-quick up /etc/wireguard/wg0.conf

Service configuration

Since Alpine 3.20, wireguard-tools-openrc package provides an OpenRC initd service file.

To use this, install the package:

# apk add wireguard-tools-openrc

To use the WireGuard OpenRC script with wg-quick.wg0, create a symbolic link to it with the configuration name as follows:

# ln -s /etc/init.d/wg-quick /etc/init.d/wg-quick.wg0

Add the wg-quick.wg0 service to the default runlevel:

# rc-update add wg-quick.wg0

To start|stop|restart the OpenRC service:

# rc-service wg-quick.wg0 start

Enable IP Forwarding

With a NAT destination rule in place on your router, you should be able connect to the wireguard instance and access the host. However, if you intend for peers to be able to access external resources (including the internet), you will need to enable ip forwarding.

Edit the file /etc/sysctl.conf or a .conf file under /etc/sysctl.d/ folder add the following line as follows:

Contents of /etc/sysctl.conf

net.ipv4.ip_forward = 1

Add the sysctl service to run at boot:

# rc-update add sysctl

Then either reboot or run # sysctl -p /etc/sysctl.conf to reload the settings. To ensure forwarding is turned on, run # sysctl -a and ensure net.ipv4.ip_forward is set to 1.

In the file /etc/conf.d/iptables, Change the setting as follows:

Contents of /etc/conf.d/iptables

... IPFORWARD="yes"

Running with modloop

If you are running Diskless Mode i.e from a RAM disk, you can't modify the modloop.

You can get around it by unpacking the modloop, mounting the unpacked modules folder, then installing WireGuard.

#!/bin/sh
apk add squashfs-tools # install squashfs tools to unpack modloop
unsquashfs -d /root/squash /lib/modloop-lts # unpack modloop to root dir
umount /.modloop # unmount existing modloop
mount /root/squash/ /.modloop/ # mount unpacked modloop
apk del wireguard-lts # uninstall previous WireGuard install
apk add wireguard-lts
apk add wireguard-tools

You can repack the squash filesystem or put this script in the /etc/local.d/ path so it runs at boot-up.

See also

• WireGuard documentation