WEP key authentication

Dan Williams dcbw at redhat.com
Thu Dec 6 19:00:58 EST 2012


On Thu, 2012-12-06 at 22:46 +0000, Sam Gardner wrote:
> Hi,
> 
> 
> I am using wpa_aupplicant to connect to wifi APs using WPA, WPA2 and
> WEP encryption. I am able to verify that the WPA/WPA2 passphrase is
> correct by checking wpa_cli status. Is there anyway I can verify that
> the WEP key is correct using wpa_supplicant or any other wireless
> tool?

No, that's simply not part of the WEP protocol.

(Though if you're using Shared Key authentication on the access points,
yes, you can figure out if it's wrong because you'll get rejected during
authentication.  But it turns out Shared Key has serious security
vulnerabilities that make it trivial to crack your WEP key, so don't use
it.  Also, most Linux drivers will cycle through WEP authentication
methods, so even if you specify Shared Key, if that fails the driver
will just retry with Open System, and you get the behavior below.)

You have to know the key beforehand, and if the key is incorrect, the
card and the AP will happily authenticate and associate, but since the
key is wrong, the AP can't decrypt any of your traffic, and you won't be
able to talk to anything.  That's just the way WEP is.  Don't use it.

Dan




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