AP <-> STA: tcpdump shows duplicate ARP request from STA,
but STA only sends one.
Monthadar Al Jaberi
monthadar at gmail.com
Fri Jun 15 09:02:46 UTC 2012
On Mon, Jun 11, 2012 at 6:28 PM, Adrian Chadd <adrian at freebsd.org> wrote:
> Hi!
>
> The "null frame" is from hostap. It sends it out whenever a new
> station (re) joins. It's a broadcast frame that's harmless, designed
> to "seed" all the switches with the true location of the MAC address.
>
> As for dup packets, I'm not sure. Hm!
mm, its weird the received frame are only tapped once in net80211 from
what I can see ...
>
>
>
> Adrian
Ok, I tried with mesh and they dont recevie these ARP Request at all... hmmm
Running two RSPRO as mesh and one RSPRO as monitor I noticed this:
Both Mesh nodes sends out ARP Requests ( I verified it by tcpdump).
These ARP Requests are seen by the monitor RSPRO:
01:22:38.020700 1357460558us tsft 1.0 Mb/s -28dB signal -96dB noise
antenna 1 2442 MHz 11g MeshData (AE 0 TTL 31 seq 1) CF +QoS ARP,
Request who-has 192.168.0.22 tell 192.168.0.22, length 28
0x0000: 0000 2000 6708 0400 4e34 e950 0000 0000 ....g...N4.P....
0x0010: 2002 e4a0 0100 0000 8004 0000 8a09 071b ................
0x0020: 8802 0000 ffff ffff ffff 0015 6d67 2173 ............mg!s
0x0030: 0015 6d67 2173 0000 00de 00de 001f 0100 ..mg!s..........
0x0040: 0000 aaaa 0300 0000 0806 0001 0800 0604 ................
0x0050: 0001 0015 6d67 2173 c0a8 0016 0000 0000 ....mg!s........
0x0060: 0000 c0a8 0016 ......
01:22:42.058109 1361496938us tsft 1.0 Mb/s -30dB signal -96dB noise
antenna 1 2442 MHz 11g MeshData (AE 0 TTL 31 seq 1) CF +QoS ARP,
Request who-has 192.168.0.23 tell 192.168.0.23, length 28
0x0000: 0000 2000 6708 0400 6acb 2651 0000 0000 ....g...j.&Q....
0x0010: 2002 e2a0 0100 0000 8004 0000 8a09 071b ................
0x0020: 8802 0000 ffff ffff ffff 0015 6d67 2175 ............mg!u
0x0030: 0015 6d67 2175 0000 00de 00de 001f 0100 ..mg!u..........
0x0040: 0000 aaaa 0300 0000 0806 0001 0800 0604 ................
0x0050: 0001 0015 6d67 2175 c0a8 0017 0000 0000 ....mg!u........
0x0060: 0000 c0a8 0017 ......
I verified that each each mesh node have not recevied the ARP Request
by tapping the link level (tcpdump -i wlan0 -y IEEE802_11_RADIO). Are
they filtered out in the begining? Do we miss an interrupt?
br,
--
Monthadar Al Jaberi
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