EAPOL frame drops in hostapd by enabling bridge

Jouni Malinen j
Fri Aug 14 13:47:55 PDT 2015

On Wed, Aug 05, 2015 at 06:32:49PM +0530, Gujrathi, Tushar IN PUN STS wrote:
> > Wireless Access Point (AP):     Runs hostapd, on wlan0 interface,
> * it has two Ethernet interfaces, namely eth0 and eth1. They are bonded together into bond0 of mode 1,
> * there is bridge br0 created for bond0

Would you be able to test this without bond0 in the picture (e.g.,
include eth0 and wlan0 in the bridge for a test run)?

The way Linux packet socket and bridge is implemented is quite
inconvenient at times and this can result in packet socket RX not
working properly when bound to a specific protocol like it is with EAPOL
frames. I've never tested this with bonding, but that sounds like the
only difference here from a setup that I know works. That said, I don't
see why bonding between the Ethernet interfaces would have such effect
on br0/wlan0.

> If I disable bridge, I am able to receive EAPOL messages on wlan0 (I have traced it through WireShark).
> By enabling the bridge, EAPOL messages get drops somewhere in path wlan0 to br0, I am not able to trace it.

How did you try to figure out where the packet gets dropped? Please note
that hostapd uses a Linux packet socked bound to a single ethertype.
That works differently compared to a packet socket that is set to
receive all protocols (which is what Wireshark would likely use).

Jouni Malinen                                            PGP id EFC895FA

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