Search Linux Wireless

Re: wpa_supplicant bridging problems

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi,

Have you tried to add wlan0 to the bridge **before**
wpa_supplicant (with the -b option) is launched ?

wpa_supplicant opens a socket to listen to EAPOL frames
in the bridge, and it does not seem to work if the interface
is not in the bridge at start.

Regards,
Simon


On 17/02/2016 04:30, J Mo wrote:

Hello everyone

I am having a very difficult time with a wireless bridging problem.

My objective is to use a Debian GNU/Linux host as a wireless ethernet bridge between itself, some hosts connected through a switch on it's eth0 port, and an OpenWRT router.

I have a test setup consisting of a laptop, a small PC (802.11 client), and the OpenWRT AP/router.

The wifi client system is an amd64(intel) with one 802.11 interface and a 1000BASE-T interface. The 802.11 hardware here is an Intel 3160. The OS is Debian GNU/Linux unstable with kernel 4.3.0-1-amd64 and wpasupplicant package version 2.3-2.3.

The 802.11 AP is a TP-Link TL-WR710N which is based off the Atheros ar9331.



My problem is the moment I bridge the wlan0 interface on the 802.11 PC client, wpa_supplicant stops doing it's job. It stops responding to any EAPOL frames from the AP, even though it seems to be receiving them.

It is noteworthy that the bridging works. I am able to get a DHCP lease on the laptop from the OpenWRT AP/router via bridging though the PC. Traffic passes both way and everything works great until the next WPA rekey event comes along (every 10 minutes by default for OpenWRT), and then the client gets deauth'ed from the AP because it fails to respond.

The only way I can get this to work is to first bring up my wlan0 interface on the PC so that wpa_supplicant authenticates itself correctly. Once the 802.11 layer 2 is up, I manually use brctl to bridge in the eth0 and wlan0 ports on the PC. Everything works fine until the AP wants to rekey or the client needs to re-auth for some reason.



Here is what my setup looks like:

The OpenWRT device setup is pretty standard. The only thing required for the bridging is the addition of the "option wds 1" parameter under the wifi-iface in the "wireless" config file. The wds parameter enables 4-address frames to allow the bridging. In case it's relevant, I'm doing WPA2 PSK AES/CCMP.

My PC/client /etc/network/interfaces file looks kind of like this:

allow-hotplug eth0
iface eth0 inet manual

auto wlan0
iface wlan0 inet manual
    wpa-debug-level 2
    wpa-ssid POTATONET
    wpa-psk XXXXXXXXX
    pre-up iw dev wlan0 set 4addr on
    pre-up iw dev wlan0 set power_save off

allow-auto br0
# iface br0 inet dhcp
iface br0 inet manual
    # bridge_ports wlan0
    bridge_ports none
    bridge_stp off
    bridge_waitport 0
    bridge_fd 0
    # wpa-iface wlan0
    # wpa-bridge br0


I bring up wlan0 and br0:

sudo ifup wlan0
sudo ifup br0

At this point, the wlan0 port should be associated to the AP, even though I don't have any layer 3 interfaces on the PC yet. If I force a re-authentication from the AP it works fine. WPA rekey works fine.

I do this to bridge up the interfaces:
    sudo brctl addif br0 eth0
    sudo brctl addif br0 wlan0

From this point on, wpa_supplicant stops working correctly. However, the bridge works and ethernet frames are being passed between the laptop off of PC port eth0 and the OpenWRT AP. Everything is fine until the WPA rekey happens and then the wlan0 interface goes down and stops working.

I did a tcpdump to find out what was going on and discovered that once the AP asked for re-authentication from the client, no traffic was going out of the wlan0 interface on the client PC. This was supported by ifconfig TX counters. wpa_supplicant stops replying to the AP on the wlan0 interface.

It should be noted at this point that I am aware wpa_supplicant is supposed to need the "-b" argument in this kind of setup, which is what the commented-out "wpa-bridge" parameter in the "interfaces" file above is for, but it didn't work. I verified the arguments given to wpa_supplicant were correct via ps:

/sbin/wpa_supplicant -s -B -P /run/wpa_supplicant.wlan0.pid -i wlan0 -b br0 -D nl80211,wext -C /run/wpa_supplicant



Additional notes and observations:

Just to be clear, I have inspected the macaddr and arp tables on both the OpenWRT AP and the laptop and the MACs are correct. The wireless bridging is definitely working as expected. Let me know if you want output from these commands, but I don't think they are relevant.

The default WPA rekey timer is every 10 minutes on OpenWRT, but I can force the AP to re-authenticate the client by doing this: ubus call hostapd.wlan0 del_client '{"addr":"34:de:1a:zz:zz:zz", "reason":1, "deauth":true, "ban_time":0}'



Finally, here is some debugging output (wpa_supplicant -ddd) from the client PC during a failed re-auth with the AP.

http://jmomo.net/files/wpa_probs.txt



What do?

If additional debugging is needed, let me know what to do. If this is a Debian package problem, let me know and I'll go open a bug there.

--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html

--
To unsubscribe from this list: send the line "unsubscribe linux-wireless" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Host AP]     [ATH6KL]     [Linux Wireless Personal Area Network]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Linux Kernel]     [IDE]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite Hiking]     [MIPS Linux]     [ARM Linux]     [Linux RAID]

  Powered by Linux