Bridging eth0 to wlan0

nwildner asked:

I’m trying to create the followig setup:

                                |  Wi-Fi   |
     +------+           +------+     |
     |      |           |      |+----+
     | VoIP |+--------->| Thin |
     |Phone |           |Client|
     +------+ Ethernet  +------+

The Thin Client and the VoIP phone shall have different ip addresses on the same subnet(the wireless one). So far what i’ve reached is, to make the br0 interface get a valid ip through dhcp, with the following commands

echo 1 > /proc/sys/net/ipv4/ip_forward

ip link set dev wlan0 up
ip link set dev eth0 up

brctl addbr br0
brctl addif br0 wlan0
brctl addif br0 eth0
ip link set dev br0 up

wpa_supplicant -B -b br0 -i wlan0 -c /home/test/my.wpa.conf
dhclient br0

Routing works, and accessing the internet or Windows terminal server from the thin client work as expected. Am i missing something that needs to be configured to the phone get a valid dhcp lease too?

Listening with tcpdump on the eth0(tcpdump -i eth0 -nevvv) i get no traffic at all, and on wlan0 doing nothing than being connected, just stp topology updates.

Other thing: Masquerade/NAT is not an option, because we want to control the phones on the dhcp, with the mac vendor filter and making they act like different hosts to avoid configuring each phone, and managing them just on the VoIP central.


My answer:

Forget this setup and buy a purpose-built device which performs the same function. These Ethernet-wireless LAN client bridge devices (which can be hard to search for since there’s no real standard name for the device’s function) range from as little as $20 USD on the low end to $1500 or more for a ruggedized industrial grade device. In an office, you probably don’t need IP68 protection, though…

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