Subject: RE: IPP> Re: IPP Scheme

From: Rich Gray <[email-masked]>
Date: Mon, 13 Jul 1998 11:05:33 -0400

> -----Original Message-----
> From: Keith Moore [mailto:[email-masked]]
> Sent: Sunday, July 12, 1998 7:39 PM
> To: Randy Turner
> Cc: [email-masked]; [email-masked]; [email-masked]
> Subject: IPP> Re: IPP Scheme 

[snips]

Keith writes:
> 
> With due respect, the IESG disagrees.  The layering of a new protocol
> over HTTP, and the proposed reuse of http: URLs, has 
> generated concerns
> about breaking widely-held assumptions - specifically, 
> firewall policies
> and assumptions about what http: means and how it is used.

What can one assume about http?  That it is the "browsing" application??
Using conventional http/html one can indeed browse a vast "library" of
information.  Many of us are now quite dependant upon this access.  But
one can also upload/download files, control routers and other gear
(including printers!), cop a peek at a porn site, get news & other
information, send and receive e-mail and all sorts of services that
imaginative people have managed to implement on these protocols.   So it
seems to me that the only meaning http: has it that it is Hypertext
Transport.  One cannot tell what is being transported.  It is not
possible to infer "application" based upon http:.  One would have to dig
into the content of the messages (or filter on hosts) to do much
effective blocking if one wanted to restrict http to a small set of
legitimate applications.   So it does not seem like this is much help
for the firewall administrator.  The barndoor is already pretty wide
open. 

MIME type would seem to provide a most adequate filtering hook for IPP
and other protocols which also wish to ride on http.  

> Keith

Another $.02,

Rich

Richard B. Gray, Sr. Software Egr.| Tel: 513/746-8118 ext. 2405
Digital Controls Corporation      | Fax: 513/743-8575
305 South Pioneer Blvd.           | Net: [email-masked]
Springboro OH 45066-1100, USA     | Http://lpplus.digital-controls.com

---

From: Keith Moore <[email-masked]>
Date: Mon, 13 Jul 1998 11:15:17 -0400

> and other protocols which also wish to ride on http.  

Filtering is not the issue with ipp: vs http:.  

The problem with using http: for printers is that it hides the fact 
that the resource is a printer.  Users then have to keep track of 
that information separately, while user agents (web clients etc.) 
are unable to take advantage of the fact that the resource is a 
printer to improve their user interfaces.

Keith

---

From: Randy Turner <[email-masked]>
Date: Mon, 13 Jul 1998 08:43:50 -0700

I can appreciate the need for compromise, given your earlier message, but
I'm not sure I completely understand the difference between your
compromise, and our "ipp:" URL usage model that we sent out to you. It
looks like you're suggesting using the HTTP header part of our proposal,
and trying to use "ipp:" URLs within the application/ipp
part where appropriate, which is basically what our usage model stated.

Could you do a "diff" on our document and your compromise for the DL?

Thanks

Randy

---

From: Keith Moore <[email-masked]>
Date: Mon, 13 Jul 1998 13:52:06 -0400

> Could you do a "diff" on our document and your compromise for the DL?

Basically, the difference is that in the compromise proposal,
the ipp: stuff never appears at the HTTP layer.  So it's not 
going to break any of the proxies or client APIs or servers.

Keith