eap Mailing List: RE: Re: comments on draft-groeting-eap-netselection-results -00.txt

[Tschofenig Hannes (hannes.tschofenig]

hi bernard, 

i know that there is a problem when you use a non-unique identifier. 
with the goal of assigning certain properties or capabilities to a network
you might want to identify it somehow. 

as you said, you could use the pair <SSID + BSSID> for this purpose (or even
the bssid alone).

since these identifiers are used for a few things (such as identification,
authentication and authorization) you might want to have a more convient
identifier which means something to an end user. otherwise you could just
use the hash of a public key and truncate it to 48 bits. such an identifier
would look ugly (for a user) but would have some security properties. 

ciao
hannes


> -----Original Message-----
> From: Bernard Aboba [mailto:aboba [at] internaut.com] 
> Sent: Tuesday, July 20, 2004 6:17 PM
> To: Tschofenig Hannes
> Cc: eap [at] frascone.com
> Subject: RE: [eap] Re: comments on 
> draft-groeting-eap-netselection-results -00.txt
> 
> > even automatic processing might be complicated if you have 
> to carry a 
> > 10mb file of <SSID + BSSID> identifiers and their services with you.
> > this also requires that you register your <SSID + BSSID> identifier 
> > pair somewhere.
> >
> > what do you think?
> 
> The SSID is a non-unique identifier.  This will affect all 
> schemes that attempt to use the SSID as an identifier of a 
> network configuration.
> It does not matter whether the schemes are dynamic or static.
> 
> In particular, there are SSIDs that ship by default on APs.  
> For those "default" SSIDs, the SSID isn't just a non-unique 
> identifier with *some* potential for duplication;  
> duplication is the intent, making the SSID meaningless for 
> network identification.  One potential mechanism for 
> dis-ambiguating "default" SSIDs is to use the BSSID ot 
> distinguish them.
> However, the implicit assumption here is that "default" SSIDs 
> are not used in large networks, but rather in situations 
> where only a small number (usually one) AP is deployed.  Thus 
> the SSID + BSSID combination may uniquely identify a single 
> AP network.
> 
> If this assumption does not hold, a host of problems arise.  
> But these problems will also afflict dynamic as well as 
> static techniques that rely on the SSID as a means of network 
> identification.
> 
> The solution to this problem is probably to utilize another 
> mechanism with guaranteed uniqueness to identify WLAN 
> networks.  However, given that the problem is fundamental to 
> 802.11, it seems likely that 802.11 will wish to become 
> involved in the solution.  The recent "straw poll" indicating 
> a desire to standardize Network Selection within 802.11 is a 
> likely indication of this.
>