Decrypt Errors with WPA2

MICHAEL SCHROEDER · ‎03-30-2009

Hi All, i see a lot of Messages in my Traplog: "Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]". Does anyone know what this means? We are using WPA2 with AES exclusively, no legacy Clients, all are 4965AGN with latest Proset. Thx and rgrds, Michael

Leo Laohoo · ‎03-30-2009

As long as the clients don't get disconnected, I believe this could be a bug. What's your firmware?

MICHAEL SCHROEDER · ‎03-30-2009

Hi, the Controllers are running on 4.2.176.0

MICHAEL SCHROEDER · ‎03-31-2009

Additionally, these Error occurs frequently every 2 minutes, as the Traplog shows:

48 Tue Mar 31 11:11:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

49 Tue Mar 31 11:09:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

50 Tue Mar 31 11:07:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

52 Tue Mar 31 11:05:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

53 Tue Mar 31 11:03:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

54 Tue Mar 31 11:01:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

55 Tue Mar 31 10:59:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

56 Tue Mar 31 10:57:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

57 Tue Mar 31 10:55:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

58 Tue Mar 31 10:53:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

59 Tue Mar 31 10:51:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

60 Tue Mar 31 10:49:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

61 Tue Mar 31 10:47:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

62 Tue Mar 31 10:45:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

63 Tue Mar 31 10:43:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

64 Tue Mar 31 10:41:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

65 Tue Mar 31 10:39:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

66 Tue Mar 31 10:37:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

67 Tue Mar 31 10:35:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

68 Tue Mar 31 10:33:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

69 Tue Mar 31 10:31:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

70 Tue Mar 31 10:29:22 2009 Decrypt errors occurred for client [MAC] using WPA2 key on 802.11a interface of AP [MAC]

Regards, Michael

Leo Laohoo · ‎03-31-2009

Hi Michael,

If you want to disable this trap logs, go to Management -> SNMP -> Trap Controls -> Security. Untick "WEP Decrypt Error".

Hope this helps.

MICHAEL SCHROEDER · ‎03-31-2009

Hi Leo, yeah, did this yesterday, since them the Problem is solved ;-))

But what does this Error mean? Is this something that happens during Security Capability Negitiation? Thx and Regards, Michael

Leo Laohoo · ‎04-01-2009

Hi Michael,

Good to hear. This error, and I'm just guessing here, is possibly caused by the "incompatibility" of the client's Wireless NIC card to the Cisco codec.

Is this happening to only one client or a number of clients?

Are they using a particular wireless NIC card or are they using a mix set?

When these clients are authenticated on the Wireless LAN, do they get dropouts?

If you go to Monitor -> Clients and then drill down to the client, under Security Information, what is the output?