Feature request: Ability to set multicast (and other?) device flags.

[Jonathan Wheeler]

Hello,

I have a site-to-site WireGuard tunnel configured and working using Netplan 0.104-0ubuntu2.1 on Ubuntu 24.04 using networkd as my backend.

In order to have AirPlay and other services visible to both ends of the tunnel, I've installed avahi-daemon on both ends, configured to reflect mDNS multicast packets. However, in order for this to work, I also need to execute "sudo ip link set wg0 multicast on" on both ends of the tunnel; there doesn't seem to be a way to specify this flag in Netplan. Once I do this, it works fine.

***It would be nice if I could set the multicast and other device flags in my Netplan config. At a minimum, Netplan should perhaps (?) automatically implicitly set this flag when a multicast route is specified, but it doesn't seem to do so. (And similarly the broadcast device flag for broadcast routes, etc?)***

In the meantime, I'll implement a workaround using networkd-dispatcher.

Thank you for your efforts. You've made setting up my dual-homed-multi-site network setup much more pleasant.

Kind regards,
Jonathan

[Lukas Märdian (slyon)]

Thanks for your input! I think using a networkd-dispatcher hook is a proper workaround for now.

I implemented the notion of "NetplanFlags" recently (part of PR#288), which we could probably re-use for a new "device-flags: [multicast, broadcast, ...]" YAML stanza: https://github.com/canonical/netplan/pull/288/commits/f155b51fee8e5f71ca829375110e225d650ce968

Do you know what is the proper setting in systemd-networkd and/or NetworkManager to enable those device flags?

"[Link].Multicast=" seems to be relevant:
https://systemd.network/systemd.network.html#Multicast=

Could you please try to confirm this setting in a sd-networkd override config? e.g.:
$ cat /etc/systemd/network/10-netplan-wg0.link.d/override.conf
[Link]
Multicast=true

[Launchpad Janitor (janitor)]

[Expired for netplan because there has been no activity for 60 days.]