Subject: [eap] WG last call issue: EAP-04 Section 5.3 - use of zero in a NAK

From: [email-masked] (Henrik Levkowetz)
Date: Tue, 17 Jun 2003 19:44:09 +0200

Submitter name: Henrik Levkowetz
Submitter email address: [email-masked]
Date first submitted: June 17, 2003
Document: EAP-04
Comment type: T
Priority: 1
Section: 5.3
Rationale/Explanation of issue:

There is various text on the use of zero in a NAK, for instance,
Section 5.3.1 says:

      "The legacy Nak Type is valid only in Response messages.  It is
      sent in reply to a Request where the desired authentication Type
      is unacceptable.  Authentication Types are numbered 4 and above.
      The Response contains one or more authentication Types desired by
      the Peer.  Type zero (0) is used to indicate that the sender has
      no viable alternatives."

Reading this, I wondered: When is the value zero used in a NAK? When the
peer doesn't want to *disclose* alternatives, or when there are none
left? May the authenticator continue probing after receiving a zero NAK?

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From: [email-masked] (Jari Arkko)
Date: Wed, 18 Jun 2003 22:31:58 +0300

> left? May the authenticator continue probing after receiving a zero NAK?

The text seems to say that the peer has no alternatives. Still,
I wonder if zero is used for other purposes as well. Has it been
used for implementations that can't  tell what methods might be
appropriate?

If not, I'd rather say SHOULD NOT probe after receiving
a zero NAK.

--Jari