problem with stats and WPA on prism

Paul Fox pgf at brightstareng.com
Thu Nov 9 12:14:56 EST 2006


once in a while (actually, fairly often) when i connect to our
linksys AP with my engenius prism card (1.8.2 or 1.8.4 firmware),
i get connectivity, but the link stats are incorrect.  this
is reminiscent of an older bug that in the 0.3.x drivers, but
i was under the impression it had been fixed.

kernel:  2.4.24, with patch for wireless extensions 18 applied
driver:  hostap-driver-0.4.9
wpa_supplicant:  v0.4.9
wireless tools: 
	
    $ iwconfig --version
    iwconfig  Wireless-Tools version 29
	      Compatible with Wireless Extension v11 to v21.

    Kernel    Currently compiled with Wireless Extension v18.

    wifi0     Recommend Wireless Extension v18 or later,
	      Currently compiled with Wireless Extension v18.

    eth1      Recommend Wireless Extension v18 or later,
	      Currently compiled with Wireless Extension v18.


when everything is working properly, i have this:

$ ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:02:6F:37:7F:A6  
          inet addr:192.168.1.58  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11225 errors:0 dropped:394 overruns:0 frame:0
          TX packets:67 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:994445 (971.1 Kb)  TX bytes:7487 (7.3 Kb)
          Interrupt:55 

$ iwconfig eth1
eth1      IEEE 802.11b  ESSID:"linksys54g"  
          Mode:Managed  Frequency:2.432 GHz  Access Point: 00:14:BF:74:25:2A   
          Bit Rate:11 Mb/s   Sensitivity=1/3  
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=38/70  Signal level=-55 dBm  Noise level=-93 dBm
          Rx invalid nwid:0  Rx invalid crypt:294  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:10271   Missed beacon:0


when the problem occurs, i have this:

$ ifconfig eth1
eth1      Link encap:Ethernet  HWaddr 00:02:6F:37:7F:A6  
          inet addr:192.168.1.58  Bcast:192.168.1.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:11346 errors:0 dropped:445 overruns:0 frame:0
          TX packets:83 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:1005990 (982.4 Kb)  TX bytes:9382 (9.1 Kb)
          Interrupt:55 

$ iwconfig eth1
eth1      IEEE 802.11b  ESSID:"linksys54g"  
          Mode:Managed  Access Point: 00:14:BF:74:25:2A   Bit Rate:11 Mb/s   
          Sensitivity=1/3  
          Retry min limit:8   RTS thr:off   Fragment thr:off
          Encryption key:off
          Power Management:off
          Link Quality=0/70  Signal level=-100 dBm  Noise level=-93 dBm
          Rx invalid nwid:0  Rx invalid crypt:298  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:10291   Missed beacon:0


note the Link Quality values.  note also the missing channel information.
connectivity is fine -- it's just the stats that are bad (as far as
i can tell.)


i can fairly easily reproduce this, with a loop that downs the interface,
kills off wpa_supplicant, then restarts it, and ups the interface again.
wpa_supplicant's config looks like:

    network={
            proto=WPA
            key_mgmt=WPA-PSK
            ssid="linksys54g"
            psk="this_is_some_passphrase"
            scan_ssid=1
    }


the behavior is independent of whether the SSID is hidden or not.

i can supply more debug or config info as needed, and am happy
to insert whatever extra debug tracing that might be required.

btw, here's an exchange i had last year with tony espy about the
similar (but more consistent) bug that i/we observed in the 0.3.X
driver:
    http://lists.shmoo.com/pipermail/hostap/2005-December/012080.html


paul
=---------------------
 paul fox, pgf at brightstareng.com



More information about the HostAP mailing list