hostapd

Jacques Caron Jacques.Caron at IPsector.com
Tue Dec 24 14:39:59 EST 2002


Hi,

At 17:04 24/12/2002, Sergio M. Ammirata wrote:
>2)      Is there a way to enable a rotating key with the m option. I dont 
>care about authenticating based on the 802.1X against a radius server, I 
>just want to leverage the rotating key functionality if the client 
>supports it to at least prevent WEP password cracking.

I don't know the details of the hostapd implementation, but I don't quite 
see how key rotation could happen without 802.1X: EAPOL-Key frames are part 
of 802.1X, and they rely on the session key negotiated between the 
supplicant (client) and the auth server (RADIUS server) within the selected 
EAP method. Without this, anybody could decrypt the key sent and this would 
not be very useful, would it?

The only other option is to have the AP and client be synchronized on keys 
that change at regular intervals, using a pre-shared seed. But that's a 
totally different thing.

>3)      Is there a way to leverage the radius client inside hostapd to 
>authenticate the MAC address for association? Right now the two options 
>are either to allow open access or to authenticate against a list of MAC 
>addresses that gets populated with iwpriv wlan0 wds_add MAC-goes-here. The 
>idea is to be able to use a central server for global authentication of 
>MAC addresses throughout a network of Access Points without having to 
>maintain the same list in each of them. I know that 802.1X does this but 
>the idea is to not have to require it on the client side. Perhaps it can 
>use radius with the MAC as Username and Password and hit the radius server 
>using PAP.

The big problem with MAC addresses is that they are so easy to change that 
it doesn't even qualify as a security feature, and certainly not for a 
large-scale setup where you need/use a central auth server.

>4)      How does the radius client inside hostapd communicate with the 
>server? Is it PAP, CHAP, MsChapV2 or am I way off in understanding how 
>this works?

Errr... RADIUS? And within RADIUS, EAP messages (exchanged between the 
supplicant and the auth server) are encapsulated in the appropriate AVPs. 
And EAP messages themselves can use one of several different methods, the 
most common being EAP-TLS, but there's also EAP-MD5 (to be avoided), 
EAP-OTP, EAP-SRP, PEAP (with another protocol within, like EAP-MSCHAPv2), 
etc. Hostapd is transparent to those message, it just passes them between 
the supplicant and the auth server, just changing the encapsulation (EAPOL 
aka 802.1X on one side, RADIUS on the other).

Hope that helps,

Jacques.


-- Jacques Caron, IP Sector Technologies
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