"So you can’t transparently bridge Ethernet devices’ MAC addresses through a WiFi client interface. This is why we need hostapd."
I think that is incorrect. hostapd handles the authentication side of things, but 4addr tuples are controlled by 'struct wireless_dev.use_4addr', and can be set by 'ip link set type bridge_slave ... proxy_arp_wifi on', `iw dev ... 4addr on', and if using systemd-networkd, with slave interface's
[Bridge]
ProxyARPWiFi=yes
(and networkd doesn't need hostapd's bridge= option since networkd handles that aspect.)
Kernel then uses NL80211_IFTYPE_AP_VLAN and handles the proxy operation.
I think that is incorrect. hostapd handles the authentication side of things, but 4addr tuples are controlled by 'struct wireless_dev.use_4addr', and can be set by 'ip link set type bridge_slave ... proxy_arp_wifi on', `iw dev ... 4addr on', and if using systemd-networkd, with slave interface's
(and networkd doesn't need hostapd's bridge= option since networkd handles that aspect.)Kernel then uses NL80211_IFTYPE_AP_VLAN and handles the proxy operation.