Kernel and systemd changes aside, I kind of want to say that you need to specify an interface for the link-local endpoint to be bound to – just as with regular sockets. If the tunnel were device-bound and not independent, that would happen by default.
It also seems weird that the tunnel has endpoints with different scopes; I think I've seen routers reject such packets with a "Scope Mismatch" error. I would try building systemd from Git source; if I remember correctly, systemd-networkd could be run directly from the build directory, making it possible to `git bisect` down to the change that fixed this. On Mon, Nov 27, 2023, 19:38 Danilo Egea Gondolfo < danilo.egea.gondo...@gmail.com> wrote: > Hello, > > I'm looking for help to understand an issue we are observing on Ubuntu > 22.04. > > networkd is failing with "netdev could not be created: Invalid argument" > when I try to create either an ip6gre or vti6 device. > > We believe this problem started when we pulled this change [1] in to the > kernel 5.15. The problem also happens with the most recent upstream kernel > so it's not an issue introduced by Ubuntu. > > The problem doesn't happen on recent versions of systemd but we'd like to > fix it on systemd 249 (used by Ubuntu 22.04). > > How to reproduce the problem (tested on Ubuntu 22.04 (jammy) with systemd > 249.11-0ubuntu3.11 and kernel 5.15.0-89-generic): > > --- /etc/systemd/network/tun0.netdev --- > [NetDev] > Name=tun0 > Kind=ip6gre > > [Tunnel] > Independent=true > Local=fe80::1 > Remote=2001:dead:beef::2 > ------ > > --- /etc/systemd/network/tun0.network --- > [Match] > Name=tun0 > > [Network] > LinkLocalAddressing=ipv6 > ConfigureWithoutCarrier=yes > ------ > > After restarting networkd I see this in the logs > tun0: netdev could not be created: Invalid argument > tun0: netdev removed > > If we boot a kernel that doesn't have [1], the interface tun0 is created. > > Here is the full log with debug enabled > https://paste.ubuntu.com/p/dPbPxgRThW/ > > As I said, the problem seems to be fixed already in systemd, but I'm > looking for help to understand what changes fixed it. > The theory is that the netlink attributes used to configure the tunnel > local/remote IPs might be wrong. > > This problem is documented here > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2037667 > > Thanks in advance. > > [1] - > https://github.com/torvalds/linux/commit/b0ad3c179059089d809b477a1d445c1183a7b8fe >
