edit: I have found that this is a duplicate of Why ARP Response only when network adapter in promiscuous mode?.
I use a Raspberry Pi 3B+ with Rasbian Stretch and set it up with proxy arp following the tutorial from Debian: Bridging Network Connections with Proxy ARP to "bridge" eth0 to wlan0. According to this it is easy to set up proxy arp with:
rpi3 ~# echo 1 > /proc/sys/net/ipv4/conf/all/proxy_arp rpi3 ~# echo 1 > /proc/sys/net/ipv4/ip_forward rpi3 ~# ip route add 192.168.10.60/32 dev eth0 192.168.10.60 is the client on eth0 that should be "bridged" to wlan0.
But it doesn't work. I have to enable promiscuous mode on wlan0 to get it to work but could not find any hints to do this.
rpi3 ~# ip link set wlan0 promisc on Is promiscuous mode needed for Stretch? If not, how can I avoid it?
updates:
Checked that rp_filter is set to 0.
hostapd is not installed. wlan0 is in client mode and managed by wpa_supplicant.