mikaela.github.io/_posts/2015-05-27-systemd-networkd.md

This is happy post so probably useless, but my blog is always so unhappy… Anyway, systemd-networkd on my hosts.

I am running systemd-networkd on wired hosts as I am not so sure how it works with wireless hosts and I am using network manager with WLAN connections.

The hosts mentioned here are * Zaldaryn which runs Ubuntu MATE 15.04 * Rbtpzn which currently runs Antergos and is the oldest PC I have and it’s also the first one ever where I installed Ubuntu 8.04 in 2008.

First you create network connection, I call them with the adapter name, e.g. Rbtpzn has /etc/systemd/network/enp0s18.network and Zaldaryn /etc/systemd/network/eth0.network.

It appears that I have been experimenting with the two hosts, so the files differ. Here is Zaldaryn which looks more proper or direct copy from Arch Wiki:

[Match]
Name=eth0

[Network]
DNS=127.0.0.1

[Address]
Address=172.16.1.6

[Route]
Gateway=172.16.0.1

and Rbtpzn

[Match]
Name=enp0s18

[Network]
Address=172.16.1.2/16
Gateway=172.16.0.1
# DNS has no effect unless systemd-resolved is used
# systemctl enable systemd-resolved && systemctl start systemd-resolved
# ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf
DNS=127.0.0.1
DNS=::1
DNS=8.8.4.4
NTP=pool.ntp.org

As you can see, they are quite different, Zaldaryn has everything neatly separated and Rbtpzn has everything in the same block.

Match specifies which network interface is in question, Address is IP address of the host. I am not sure where I took NTP and as the Rbtpzn block says, you must use systemd-resolved for the DNS settings to do anything, but that is easy, just run as root (or prefix all three commands with sudo):

update on 2015-06-07: to use NTP, you use systemd-timesyncd which is enabled with timedatectl set-ntp true.

systemctl enable systemd-resolved && systemctl start systemd-resolved
ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf

The address can also have CIDR specified which probably should be done, but it appears that systemd-networkd can guess it correctly as everything works with Zaldaryn which doesn’t have it specified.

I am also using systemd-networkd-wait-online.service (systemctl enable systemd-networkd-wait-online.service) so network.target means that I have IP address before boot continues. There is 90 second timeout, but I still don’t feel like trying this with wireless host as I would have 90 seconds longer boot time in new environments.

Update on 2015-06-07: on wireless hosts I am using Network Manager and it appears that NetworkManager-wait-online.service (systemctl enable NetworkManager-wait-online.service) works well and I shouldn’t be in new environments so often that the 90 seconds timeout would cause more harm than good.

Currently the only thing using network.target for me is Reflector service from Archwiki which updates mirrorlist with the fastest last synced mirrors on boot on Rbtpzn.

Sources/further reading * https://wiki.archlinux.org/index.php/Systemd-networkd * http://www.freedesktop.org/software/systemd/man/systemd.network.html * https://wiki.freedesktop.org/www/Software/systemd/NetworkTarget/ * https://wiki.archlinux.org/index.php/Reflector#Systemd_Service