FWIW, it appears that this is indeed possible via the [Network]DefaultRouteOnDevice setting:
/usr/sbin# cat /etc/systemd/network/eth0.network.dhcp [Match] Name=eth0 KernelCommandLine=!nfsroot [Network] DHCP=ipv4 LinkLocalAddressing=ipv4 DefaultRouteOnDevice=true [DHCP] ClientIdentifier=mac RouteMetric=10 On Mon, Jun 10, 2024 at 1:52 PM Bill Plunkett <b...@plunkware.com> wrote: > I have a yocto-hardknott (systemd v247) embedded system using link local > addressing. Undirected UDP broadcasts (i.e. dest ip = 255.255.255.255) are > failing with a 'Network is unreachable' error. I've been able to fix this > with the 'route add' command shown below, but would prefer to automate it > with systemd. Any help is greatly appreciated. > > This command allows undirected broadcasts: > > route add -net 255.255.255.255 netmask 255.255.255.255 dev eth0 > > systemd configuration: > > [Match] > Name=eth0 > KernelCommandLine=!nfsroot > > [Network] > DHCP=ipv4 > LinkLocalAddressing=ipv4 > > [DHCP] > ClientIdentifier=mac > RouteMetric=10 >
