RE: Auth method negotiation

["Julian Satran" <Julian_Satran@il.ibm.com>]

Bob,

Comments in text.

Thanks,
Julo

"Robert D. Russell" <rdr@io.iol.unh.edu> 06/22/2002 06:25 PM Please respond to "Robert D. Russell"

To:        Julian Satran/Haifa/IBM@IBMIL         cc:        ips@ece.cmu.edu         Subject:        RE: Auth method negotiation

Julian:

Just two minor comments -- in the very last sentence of
your suggested text ends with "and the protocol version".
Why is this necessary -- doesn't every Login response
have to carry identical values for version-max and
version-active?  Is the value in version-active
what you mean by "protocol version"?  If so, I would just
omit this phrase (because it raises the question as to
whether or not previous Login responses need to carry
version-active).

+++ Version selected - the initiator has version min and max in the Login request.
I should perhaps add selected +++

Second comment -- the term "session id".  Do you mean the TSIH?
If so, I believe it should say TSIH explicitly.  If not, then
what do you mean  - the full ISID/TSIH?  If so, then again
this is misleading because all Login Responses have to carry
the ISID offered in the first Login Request.

+++ I will replace session ID with TSIH +++
Thanks,
Bob Russell


On Sat, 22 Jun 2002, Julian Satran wrote:

>
> How about the following text:
>
>           -When the initiator considers that it ready to conclude the
>             SecurityNegotiation stage it sets the T bit to 1 and the NSG to
>             what it would like the next stage to be. The target will then
>             set the T bit to 1 and set NSG to the next stage in the Login
>             response where it finishes sending its security keys. The next
>             stage selected will be the one the target selected. If the next
>             stage is FullFeaturePhase, the target MUST respond with a Login
>             Response with the Session ID and the protocol version.
>  Julo
>
>
>
>                       pat_thaler@agilen
>                       t.com                    To:       wrstuden@wasabisystems.com, chirag.wighe@windriver.com
>                       Sent by:                 cc:       ips@ece.cmu.edu
>                       owner-ips@ece.cmu        Subject:  RE: Auth method negotiation
>                       .edu
>
>
>                       06/22/2002 03:01
>                       AM
>                       Please respond to
>                       pat_thaler
>
>
>
>
>
> Bill,
>
> I agree that the target made an error in sending T=1 when it chose an
> authentication method.
>
> However, even if it was willing to skip negotiation it must return CHAP
> when offered AuthMethod=KRB5,SRP,CHAP,None.
>
> 4.3.2 says "-The target MUST reply with the first option in the list it
> supports and is allowed to use for the specific initiator
> unless it does not support any in which case it MUST answer
> with "Reject" (see also Section 4.2 Text Mode Negotiation).
> The parameters are encoded in UTF8 as key=value. For security
> parameters, see Chapter 10."
>
> So if the target supports CHAP and is allowed to use CHAP for an initiator
> it MUST reply with CHAP or an earlier alternative in the list when offered
> CHAP before None for AuthMethod. It cannot reply None. If the initiator
> would have preferred "None" over "CHAP" it should have placed it before
> CHAP in the list.
>
> I think that the next text in 4.3.2 is a bit confusing:
> "-The initiator must be aware of the imminent completion of the
> SecurityNegotiation stage and MUST set the T bit to 1 and the
> NSG to what it would like the next stage to be. The target
> will answer with a Login response with the T bit set to 1 and
> the NSG to what it would like the next stage to be. The next
> stage selected will be the one the target selected. If the
> next stage is FullFeaturePhase, the target MUST respond with
> a Login Response with the Session ID and the protocol version."
>
> I think "aware of imminent completion" means that the target has sent its
> last key=value of the security negotiation but it doesn't seem a very clear
> way to say it.
> Also, the next sentence is not always true. The target might not be ready
> to set the T bit in the answering Login Response. It might have required
> more than one PDU to send its final key(s) of the security negotiation.
> "The target will then set the T bit to 1 and set NSG to the next stage in
> the Login response where it finishes sending its security keys." would be
> more accurate.
>
> Pat
>
> -----Original Message-----
> From: Bill Studenmund [mailto:wrstuden@wasabisystems.com]
> Sent: Friday, June 21, 2002 4:19 PM
> To: Chirag Wighe
> Cc: ips@ece.cmu.edu
> Subject: Re: Auth method negotiation
>
>
> On Fri, 21 Jun 2002, Chirag Wighe wrote:
>
> > Hi
> >
> > I am sorry for the typo but I cut and paste from the spec. In the spec on
> > page 245 for example it says
> > If the initiator authentication is successful, the target proceeds:
> > T- Login (CSG,NSG=0,1 T=1)
> > I- Login (CSG,NSG=1,0 T=0)
>
> Oh, if T=0, then NSG is reserved, and should have the value 0.
>
> > ... iSCSI parameters
> > T- Login (CSG,NSG=1,0 T=0)
> > ... iSCSI parameters
> >
> > I did a search and there are several other 1,0 transitions in the spec.
>
> Were they transitions, i.e. T=1? Or just notifications of continuing
> operational parameter negotiation? That's what (CSG,NSG=1,0 T=0) is.
>
> > Anyway what I meant was what Bill intepreted it to be which was
> > Login (CSG,NSG=0,1 T=1)
> > InitiatorName=iqn.1999-07.com.os.hostid.77
> > TargetName=iqn.1999-07.com.acme.diskarray.sn.88
> > AuthMethod=KRB5,SRP,CHAP,None
> >
> > and the target replying
> > T- Login-PR (CSG,NSG=0,1 T=1)
> > AuthMethod=CHAP
> >
> > and then my other questions hopefully make more sense.
>
> I think the concensus is that the target made an error. If it was willing
> to skip security negotiations (T=1, NSG=1), it shouldn't have chosen CHAP.
>
> Take care,
>
> Bill
>
>
>
>