Debian

WireGuard Server: Debian

In this tutorial, we setup a WireGuard service on a Debian server. This example uses “vanilla” Debian Buster.

At the end of this tutorial, the Debian server will have a virtual network interface wg0 living on private network 10.0.2.0/24. The Debian server will be ready to add WireGuard clients.

Platform

Install sudo

In this tutorial, we execute all commands as a non-root user with help from the sudo command. Debian doesn’t always come with sudo installed.

Check that sudo is installed.

$ sudo
-bash: sudo: command not found

In this example, the sudo command is missing. To fix, login as root, either via login prompt or via su - (which requires the root user password).

# apt install sudo
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
  sudo
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
...
Setting up sudo (1.8.27-1+deb10u1) ...
Processing triggers for man-db (2.8.5-2) ...
Processing triggers for systemd (241-7~deb10u2) ...

Enable sudo

By default, Debian does not allow non-root users to use the sudo command.

Check your non-root user. In this example, the non-root user is jacob. Login in as the non-root user and run groups.

$ groups
jacob cdrom floppy audio dip video plugdev netdev

If the sudo group is included in this list, then the non-root user can use sudo. In the above example, the group sudo does not appear. To fix, login as root, either via login prompt or via su - (which requires the root user password).

# adduser jacob sudo

Logout the root user. If su - was used to run adduser then also logout the non-root user. Login as the non-root user and run groups again.

$ groups
jacob cdrom floppy sudo audio dip video plugdev netdev

In the above example, the group sudo appears where it was missing before.

Setup WireGuard

Install WireGuard

To install the most recent version of WireGuard, we’ll need packages from the Debian unstable release. Add the Debian unstable release, and pin the Debian unstable priority behind Raspbian stable. This allows us to install packages that are not available in Debian stable, while keeping the “stable” versions of everything else.

$ sudo sh -c "echo 'deb http://deb.debian.org/debian/ unstable main' >> /etc/apt/sources.list.d/unstable.list"
$ sudo sh -c "printf 'Package: *\nPin: release a=unstable\nPin-Priority: 90\n' >> /etc/apt/preferences.d/limit-unstable"

Update package information from both stable and unstable package repositories.

$ sudo apt update
Get:1 http://deb.debian.org/debian unstable InRelease [142 kB]
Hit:2 http://archive.raspberrypi.org/debian buster InRelease
Hit:3 http://raspbian.raspberrypi.org/raspbian buster InRelease
Get:4 http://deb.debian.org/debian unstable/main armhf Packages [7,977 kB]
Get:5 http://deb.debian.org/debian unstable/main Translation-en [6,192 kB]
Fetched 14.3 MB in 22s (655 kB/s)
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.

Install the WireGuard packages. After this step, man wg and man wg-quick will work and the wg command gets bash completion.

$ sudo apt install wireguard --assume-yes
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  dkms raspberrypi-kernel-headers wireguard-dkms wireguard-tools
Suggested packages:
  python3-apport menu
The following NEW packages will be installed:
  dkms raspberrypi-kernel-headers wireguard wireguard-dkms wireguard-tools
0 upgraded, 5 newly installed, 0 to remove and 0 not upgraded.
...
DKMS: install completed.
Module build for kernel 4.19.75-v8+ was skipped since the
kernel headers for this kernel does not seem to be installed.
Setting up wireguard-tools (0.0.20191219-1) ...
Setting up wireguard (0.0.20191219-1) ...
Processing triggers for man-db (2.8.5-2) ...

Create Keys

In every client/server relationship, each peer has it’s own private and public keys. Create private and public keys for the WireGuard service. Protect the private key with a file mode creation mask.

$ (umask 077 && wg genkey > wg-private.key)
$ wg pubkey < wg-private.key > wg-public.key

Print the private key, we’ll need it soon.

$ cat wg-private.key
qPF9uU7qsCbw3uKR1t2Q0gfr2HasTKZGPkCHz2AszUs=

Create the WireGuard Network Device

Create the WireGuard service config file at /etc/wireguard/wg0.conf. (Use a command like sudo nano /etc/wireguard/wg0.conf.)

# define the WireGuard service
[Interface]

# contents of file wg-private.key that was recently created
PrivateKey = qPF9uU7qsCbw3uKR1t2Q0gfr2HasTKZGPkCHz2AszUs=

# UDP service port; 51820 is a common choice for WireGuard
ListenPort = 51820

Create the WireGuard network device at /etc/network/interfaces.d/wg0. (Use a command like sudo nano /etc/network/interfaces.d/wg0.)

# indicate that wg0 should be created when the system boots, and on ifup -a
auto wg0

# describe wg0 as an IPv4 interface with static address
iface wg0 inet static

        # static IP address 
        address 10.0.2.1/24

        # before ifup, create the device with this ip link command
        pre-up ip link add $IFACE type wireguard

        # before ifup, set the WireGuard config from earlier
        pre-up wg setconf $IFACE /etc/wireguard/$IFACE.conf

        # after ifdown, destroy the wg0 interface
        post-down ip link del $IFACE

Start WireGuard.

$ sudo ifup wg0

At any time, verify that the WireGuard configuration for wg0 is what you expect:

$ sudo wg show wg0
interface: wg0
  public key: 2efuG9OYmMPQpbkJ8CVxGlvQflY6p1u+o4wjcgGII0A=
  private key: (hidden)
  listening port: 51820

At any time, verify that the wg0 network interface exists.

$ ip address show dev wg0
  7: wg0: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1420 qdisc noqueue state UNKNOWN group default qlen 1000
      link/none
      inet 10.0.2.1/24 brd 10.0.2.255 scope global wg0
         valid_lft forever preferred_lft forever