EAP-Kerberos

[Thomas Otto]

Hi Chris, Saber, Sam, all,

(sth went wrong with my first email, I try it again)


I read your discussion in the Kerberos Mailing List regarding 
Kerberos for Wireless Authentication (June 2005). In February 05, 
I already thought a little bit about using Kerberos as single 
logon for both
* gaining access to a wireless network and
* using the offered kerberized services,
so that I began writing an EAP method which uses Kerberos, 
(the draft is at http://www-public.tu-bs.de:8080/~y0013790/ ,
but so dramatically immature that it is not worth to be read ;-).

There are generally two ways how to apply Kerberos to WLAN
authentication: 

1) The user has nothing but his username/password. The EAP-
conversation is carried out in order to authenticate at the 
AS and to get a TGT. 
>From this point, the client uses this TGT to request the TGS
for service tickets. 

2) The user has already network access and a TGT. In this case,
the authenticator (access point) is a service, so that the 
goal is to get a service ticket for the service "access point,
wireless network access".
Therefore, a proxy Kerberos Server is inside the access point
and talks EAP to the client, and talks in the other direction
over IP with the Kerberos TGS. (I think this is covered by 
an older proposal, EAP-GSS).

Case 1 is interesting. It would be nice if a user types only 
once, namely at the initial logon, his username password, and 
subsequently get access to the network and the therein 
advertised services. 

Is this situation realistic? 

Where could one use Kerberos in wireless authentication otherwise?

I'd be glad if you tell me your ideas, and especially if you see the
need for an EAP Kerberos method. 

Best regards,
Thomas


PS. I'm aware of the property catalogue for an EAP method, which is intended
to be used in wireless networks ( http://www.ietf.org/rfc/rfc4017.txt ).
The major issue is the dictionary attack problem, but I think it could be
mitigated by using some strong password protocol (like the paper of Wu it 
proposes).