WPA-PSK reconnection problem

Michael Guntsche mike at it-loops.com
Sat May 29 12:06:45 EDT 2004


Hello list,

I am facing a strange problem regarding my WPA-PSK set- up here.
I have two notebooks connecting to a Hostap-AP running hostapd
with WPA enabled.
If the notebooks connect to the AP the first time everyhing works, they 
can talk to each other, reach the internet....
Rekeying works too. I changed wpa_group_rekey to 60 seconds to test 
that.
Now for the problem. If one of the notebooks is sleeping/turned off 
while the GTK key changes it's no longer able to reconnect. (the 
notebook running linux/winXP does
sometimes)

Running hostapd with -dd shows (with the powerbook)

Working system:
<Server running>
<Notebook connects>
Configuration file: /usr/local/etc/hostapd.conf
Using interface wlan0ap with hwaddr 00:09:5b:2f:13:1f and ssid 'vortex'
Flushing old station entries
Deauthenticate all stations
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: authenticated
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: associated (aid 1)
wlan0: STA 00:0d:93:83:92:7a WPA: pairwise key handshake completed
Plaintext EAPOL-Key Key Data - hexdump(len=32): 0d f1 46 f3 56 71 3f 1f 
e6 50 0b d1 f8 ac 5d 37 69 fa de 99 71 f6 4a 50 76 e7 c7 63 eb 26 de 17
wlan0: STA 00:0d:93:83:92:7a WPA: group key handshake completed

<rekeying>
Plaintext EAPOL-Key Key Data - hexdump(len=32): 6d e9 fc 9b 32 b8 5d 6d 
3c 62 8e d4 0f e5 27 87 df 07 de 97 1a 40 6f 13 c7 ce 88 32 90 83 99 8a
wlan0: STA 00:0d:93:83:92:7a WPA: group key handshake completed



Non working system:
<Server running>
<Notebook connects>
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: authenticated
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: associated (aid 1)
wlan0: STA 00:0d:93:83:92:7a WPA: pairwise key handshake completed
Plaintext EAPOL-Key Key Data - hexdump(len=32): 00 2d 2d 0a 58 63 b0 00 
51 b2 26 ca 4d b2 fe 89 d6 6d 87 4f 8e 29 4c 54 3a 6c 2e d1 c4 aa ce 5d
wlan0: STA 00:0d:93:83:92:7a WPA: group key handshake completed

<two rekeyings>
Plaintext EAPOL-Key Key Data - hexdump(len=32): d4 10 d1 49 a9 e5 f4 e3 
83 87 87 c0 fc 93 b0 23 4f 95 40 bc 9e 35 cf a0 69 e8 b1 f6 da ad 19 27
wlan0: STA 00:0d:93:83:92:7a WPA: group key handshake completed
Plaintext EAPOL-Key Key Data - hexdump(len=32): fa d6 48 97 c4 df 65 04 
b9 f7 d9 4b 1c d0 f1 15 4d 70 ea 95 1a 6a b8 e8 59 b6 7e 0d 68 f6 09 c2
wlan0: STA 00:0d:93:83:92:7a WPA: group key handshake completed

<Now we turn off the wireless card>
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: disassociated

<After 30 seconds I see the last GTK change, no host is connected>
Plaintext EAPOL-Key Key Data - hexdump(len=32): 33 98 e9 47 0d c0 2c 78 
93 29 0e ba 88 b8 28 31 ad 07 b4 95 5f 81 11 63 b3 e1 df 37 eb b4 0d 10

<Now I enable the wireless card again>
Failed to set encryption. <-- I don't know what this means exactly
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: authenticated
wlan0: STA 00:0d:93:83:92:7a IEEE 802.11: associated (aid 1)
wlan0: STA 00:0d:93:83:92:7a WPA: pairwise key handshake completed

As you can see,  there is now group key handshake taking place and I 
have no connection.

I see this behaviour with:

	Notebook A:
		 Linux + Prism Card + hostap cvs + wpa_supplicant cvs
		 WindowsXP + WPA-patch + ipw2100
	The behaviour is a little bit different here, but I still can't 
reconnect	
	Notebook B:
		Apple G4 Airport Extreme

Right now I am back to running in WEP mode, but I would really like to 
get WPA-PSK
up and running.
Maybe it is just a misconfiguration on my side, so any help is gladly 
appreciated.


Thanks in advance,
Michael




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