IPP> Reopen IPP Bake-off decision for authentication

IPP> Reopen IPP Bake-off decision for authentication

IPP> Reopen IPP Bake-off decision for authentication

Adams, Charles A charles.a.adams at opbu.xerox.com
Thu Oct 26 16:28:31 EDT 2000


	Hi everyone. This is just one opinion from Xerox for your

Chuck Adams
Office Printing Business
Xerox Corporation


From: Taylor, Ross E 
Sent: Thursday, October 26, 2000 8:50 AM
To: Adams, Charles A; Glass, Brian R
Subject: RE: IPP> Reopen IPP Bake-off decision for authentication

This is a bad decision from our standpoint, and I think for IPP as a whole.
Since we have one IPP URL, "/", this does not allow us to ever authenticate
different requests differently.  There cannot be a different password for
administrators and users, based on the type of IPP request.  We also use "/"
for CentreWare IS, so authentication would have to be turned on for IPP and
for CentreWare IS at the same time, using the same username and password.
This would effectively require administrator access in order to print over

The alternative is to require special URL's for printing and/or disallow IPP
printing over port 80, all of which makes it harder for the user to set it

Since an empty request for IPP is asking for nothing, it seems reasonable
that no authentication is required.  I am not sure whether we actually have
a problem with this, since the client that was using this method was having
other problems with us and eventually worked.

Ross Taylor                  | "Gods manifest themselves in many forms,
Ross.E.Taylor at opbu.xerox.com |  Bring many matters to surprising ends;
(503) 685-3586               |  The things we thought would happen
Xerox, Inc.                  |     do not happen..."  The Bacchae, Euripides
This message does not necessarily represent the opinion of Xerox, Inc.

-----Original Message-----
From: Adams, Charles A 
Sent: Thursday, October 26, 2000 8:18 AM
To: Taylor, Ross E; Glass, Brian R
Subject: FW: IPP> Reopen IPP Bake-off decision for authentication

Is this proposal OK with us?

Chuck Adams

-----Original Message-----
From: Herriot, Robert [mailto:Robert.Herriot at pahv.xerox.COM] 
Sent: Wednesday, October 25, 2000 5:22 PM
To: IPP Discussion List (E-mail)
Subject: IPP> Reopen IPP Bake-off decision for authentication

At the recent IPP bake off the following issue came up.

Some clients determined if a Printer requires authentication by sending an
empty HTTP request. Some Printers treated this as an error.  The resolution
was for clients to send a ValidateJob operation and by inference to allow
Printers to reject empty HTTP requests.

I raised the issue about whether a Printer should perform the authentication
challenge based solely on the URL or whether it could react differently to
an empty request than to a Validate-Job request.

I asked an HTTP expert and received the following information.

   1) An HTTP server can have any policy. 
      This means that our decision is allowable.

   2) It is best for a client if it can associate the URL tree with 
      the authentication space. 

      This means that our decision could be better. That is, we should 
      require an IPP Printer to decide whether to issue an authentication 
      challenge by examining the URL and nothing else, e.g. a Printer
      receiving a request for a particular URL, gives the same 
      challenge to an empty request as to a Validate-Job request.

This solution allows a client to use Validate-Job to request a challenge as
we decided to allow. It also allows a client to use the empty request. 

The important difference between our decision and what I am proposing is
that the Printer must perform an authentication challenge consistently for a
URL regardless of the contents of the message body. This rule make IPP
behavior consistent with good HTTP policy.

Bob Herriot

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