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Systemd network management and container handling

Startup Aids

Article from ADMIN 33/2016

By Thorsten Scherf

Version 219 of the controversial systemd init system introduces a number of comprehensive changes. We take a closer look at the innovations in network management and container handling.

Most of the new features in the current version of systemd relate to the systemd-networkd and systemd-nspawn components, which have been part of systemd for a long time. However, additional functions were added to the current release that can significantly simplify working with these tools.

Setting Up Bridge Devices

The systemd-networkd network manager can now handle a variety of different network devices; its functionality has been upgraded to better support smooth operations in container environments. The following example shows how easily the daemon can be used to set up, say, a bridge device.

Networkd is not designed to replace the established Gnome NetworkManager. Instead, the daemon is intended for special environments, such as container hosts or embedded applications. Listing 1 shows the preparatory work needed to use the new network manager. For name resolution, it relies on the LLMNR (link-local multicast name resolution)-capable stub resolver, which also belongs to the systemd package.

Listing 1

Basic Setup

systemctl enable systemd-networkd
systemctl disable NetworkManager
systemctl enable systemd-resolved
cp /etc/resolv.conf /etc/resolv.conf.bak
ln -sf /run/systemd/resolve/resolv.conf /etc/resolv.conf
mkdir /etc/systemd/network

Listings 2 and 3 show the two configuration files for the regular Ethernet card (Listing 2) and bridge device (Listing 3). You can specify which device is

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