Enchancements to ifupdown in systemd

ifup-all-auto.service

This systemd unit should make sure that all of the network interfaces that are enabled by allow-auto parameter are up before the network-online.target is reached. This makes that target usable on Debian/Ubuntu hosts; services that depend on that target should work properly with the assumption that the host has network connectivity at that point.

ifup-allow-boot.service

This systemd unit will bring up all network interface that are marked by allow-boot and allow-hotplug parameters at system boot time. It is run after the networking.service unit and will use the command systemctl start ifup@<interface>.service to start the interfaces, so that any processes that are attached to them will be put in their separate cgroups. This allows better network management on systemd hosts.