Debian laptop networking setup

debian_laptop_networking_setup.md

This guide describes how to setup networking under Debian Linux on a laptop. While there are many options to choose from, Debian 12 (bookworm) uses NetworkManager and wpa_supplicant as a default. This guide installs systemd-networkd and iwd, with the goal of controlling networking form the command line, using modern components.

The official Debian documentation lists various options and serves as a starting point.

NetworkManager → systemd-networkd

Replacing NetworkManager with systemd-networkd has been done following the official Debian docs and a great guide by Fernanto Cejas.

First, disable NetworkManager and enable systemd-networkd.

$ sudo systemctl disable --now NetworkManager
$ sudo systemctl enable --now systemd-networkd

Note: the --now switch to enable or disable will also start or stop the component. Just enabling or disabling a component won't start or stop that component. I.e. --now is a shortcut for stop and disable, or start and enable, respectively.

Next, enable systemd-resolved for name resolution. You may have to install the systemd-resolved package first.

$ sudo apt install systemd-resolved
$ sudo systemctl enable --now systemd-resolved

The systemd-resolved daemon stores resolve configuration at /run/systemd/resolve/resolv.conf. Since many applications rely on finding that information at /etc/resolv.conf, it is common practice to create a symlink.

$ sudo ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

Finally, let's check the status of networking. The machine shown here has wireless networking (wlan0), a SIM card slot (wwan0), and is connected to a docking station (enx3ce1a1c25d11) and also has an ethernet port (enp0s31f6).

$ networkctl 
IDX LINK            TYPE     OPERATIONAL SETUP      
  1 lo              loopback carrier     unmanaged
  2 enp0s31f6       ether    no-carrier  unmanaged
  6 docker0         bridge   no-carrier  unmanaged
 14 wlan0           wlan     off         unmanaged
 15 wwan0           wwan     off         unmanaged
 16 enx3ce1a1c25d11 ether    routable    unmanaged

Configure the wired connections (en*) to receive an IP address via DHCP. Create the config file /etc/systemd/network/en.network. Wildcards are supported, e.g. en* matches both enx3ce1a1c25d11 and enp0s31f6.

$ cat /etc/systemd/network/en.network 
[Match]
Name=en*

[Network]
DHCP=yes

Finally, restart systemd-networkd and check, if everything works as expected.

$ sudo systemctl restart systemd-networkd

$ networkctl 
IDX LINK            TYPE     OPERATIONAL SETUP      
  1 lo              loopback carrier     unmanaged
  2 enp0s31f6       ether    no-carrier  configuring
  6 docker0         bridge   no-carrier  unmanaged
 14 wlan0           wlan     off         unmanaged
 15 wwan0           wwan     off         unmanaged
 16 enx3ce1a1c25d11 ether    routable    configured 

wpa_supplicant → iwd

ToDo.