Subject: RE: [midcom] Semantics: CHOOSE the destination?

From: "Tom-PT Taylor" <[email-masked]>
Date: Wed, 17 Jul 2002 02:45:25 -0400

You definitely describe the behaviour I assumed.  In my mind, the apparent
inconsistency lies in my use of the term "destination address" for the third
address in the tuple.  I thought of "destination" as the ultimate
destination of the packet, rather than what appears in the destination field
of the packet at its origin.  I'll think about whther I should
redefine/reorder the fields of the filter tuple to produce more consistent
behaviour.   

-----Original Message-----
From: Bob Penfield [mailto:[email-masked]]
Sent: Tuesday, July 16, 2002 5:28 PM
To: midcom
Subject: [midcom] Semantics: CHOOSE the destination?

In sec 2.3 of draft-taylor-midcom-semantics-00.txt, it indicates that the
MIDCOM Agent can request an address+port for the mapped address. If the
source and destination of a packet are matched against the source and
destination of a Policy Rule Filter, the destination address for operation
d) & e) of scenario [3:7-2] (NAPT control) would need to "CHOOSE" the
destination address. The mapped address would be the internal endpoint
address + port.

If the middlebox is suppose to match the received packet's destination with
the mapped address of the filter, the usage of the components of the filter
would be inconsistent between a firewall pinhole and a NAT translation.

For an inbound NAT, a packet match would be:
     src=<source>, dest=<mapped>

For an inbound pinhole, outbound pinhole, and outbound NAT,
a packet match would be:
     src=<source>, dest=<destination>

There seems to be the same inconsistency in the Stiemerling draft.

Or is there not suppose to be a direct relationship between the filter
fields and what the middlebox uses to match packets to rules?

Forgive me if I am being dense.

cheers,
(-:bob

Robert F. Penfield
Chief Software Architect
Acme Packet, Inc.
130 New Boston Street
Woburn, MA 01801
[email-masked]

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From: Scott Brim <[email-masked]>
Date: Wed, 17 Jul 2002 16:31:09 +0900

> redefine/reorder the fields of the filter tuple to produce more consistent

You have no idea what was in the packet at its origin.  You mean, when
it arrives at the middlebox?