network: add default .network file matching ID_NET_AUTO_LINK_LOCAL_ONLY=1

This is name ".network.example" for now, to match the existing
80-ethernet.network file.

I think it would make sense to actually install this by default if told
so via a meson file (and then hopefully this would happen even on
Fedora, though in a split off RPM or so). However, we aren't there yet,
hence for now, just ship the .network files as example, like the others.

diff --git a/network/80-auto-link-local.network.example b/network/80-auto-link-local.network.example
new file mode 100644 (file)
index 0000000..7f6a14a
--- /dev/null
+++ b/network/80-auto-link-local.network.example
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: MIT-0
+#
+# This example config file is installed as part of systemd.
+# It may be freely copied and edited (following the MIT No Attribution license).
+#
+# To use the file, one of the following methods may be used:
+# 1. add a symlink from /etc/systemd/network to the current location of this file,
+# 2. copy the file into /etc/systemd/network or one of the other paths checked
+#    by systemd-networkd and edit it there.
+# This file should not be edited in place, because it'll be overwritten on upgrades.
+
+# Enable IPv4LL + IPv6LL (but no DHCP/IPv6RA) for local links
+[Match]
+Type=ether
+Property=ID_NET_AUTO_LINK_LOCAL_ONLY=1
+
+[Network]
+LinkLocalAddressing=yes
+DHCP=no
+IPv6AcceptRA=no
+MulticastDNS=yes