RAs trigger neighbor discovery which allows users to query the
LL address of the container/VM via `ip neighbor get dev`. This is
useful as it gives users an easy way to connect to the container
without needing LLMNR or mDNS to resolve the hostname of the container
to an IP address. In practice, this allows connecting with only
networkd enabled and without resolved running in the host/container.
This changes the default .network files we ship for nspawn containers to set
EmitLLDP=customer-bridge in order to allow propagation of the LLDP packets
across bridges. This is useful so that "networkctl status" shows all peers
connected to a virtual container network, collecting this data via LLDP. This
is safe since the default configuration for these interfaces does not bridge
these links to external interfaces, but relies on IP routing for this.
'LinkLocal' was renamed to 'LinkLocalAddressing' in:
commit 56fd6bf795
Author: Tom Gundersen <teg@jklm.no>
Date: Sat Feb 14 00:32:26 2015 +0100
networkd: .network - rename LinkLocal to LinkLocalAddressing
..but apparently the network files were not updated. Fix this.
This allows both IPv4 and IPv6 link-local addresses to be enabled or disabled. By default
we still enable IPv6LL and disable IPv4LL. The old config option is kept for backwards
compatibility, but removed from the documentation.
This adds two new settings to networkd's .network files:
IPForwarding=yes and IPMasquerade=yes. The former controls the
"forwarding" sysctl setting of the interface, thus controlling whether
IP forwarding shall be enabled on the specific interface. The latter
controls whether a firewall rule shall be installed that exposes traffic
coming from the interface as coming from the local host to all other
interfaces.
This also enables both options by default for container network
interfaces, thus making "systemd-nspawn --network-veth" have network
connectivity out of the box.
