ietf-mxcomp
[Top] [All Lists]

Re: draft minutes of the MARID interim meeting on May 19 & 20

2004-05-24 09:09:47

Attached are the draft minutes of the MARID interim meeting of May 19 & 20.

Thanks.  I translated them to ASCII so people without Macs can read them.

Regards,
John Levine, johnl(_at_)taugh(_dot_)com, Taughannock Networks, Trumansburg NY
http://www.taugh.com

================
Minutes of the MARID Interim Meeting -- May 19 & 20, 2004

Chairs:
        Andy Newton
        Marshall Rose

Scribe:
        Marshall Rose

Jabber Logs:
        http://www.xmpp.org/ietf-logs/marid/2004-05-19.html
        http://www.xmpp.org/ietf-logs/marid/2004-05-20.html

Room Hums:
From item 4: support for being able separately express legitimate, 
illegitimate, and unknown 
IP addresses.
From item 5: support for a hint regarding a reputation/accreditation service.
From item 9: positive feedback on the merged SPF/Caller-ID plan.
From item 11: support for a "wildcard-like" function.


Item 1: Agenda Bashing

Andy put forward the following draft agenda: agenda bashing, notes
from the chair, semantics with subitems of bounce address tag
validation and the 30% solution, DNS record type discussion, and
syntax.  The expectation was that the first day was to cover up to the
semantics, and the second day would lead off with a DNS discussion.
Andy also noted that the agenda would be fluid and would probably
change as the meeting progressed.

Dave Crocker asked for time for a discussion on regarding the problems
being solved by the each proposal by decomposing the mechanisms used
in the proposals.  Based on the sense of the room, Andy asked for that
topic to be covered after the DNS topic.

Item 2: Chair notes

Andy simply asked the room to be courteous and professional and
remember that all participants should be in the room for the purpose
of working toward consensus.

Item 3: Bounce Address Tag Validation -- Dave Crocker presenting

The main concept on this item is that the bounce address
(2821.MAILFROM) is to be signed.  The syntax would be:

        as = <local-part> "/" <sig-type> "/" <sig-value>

The local part is opaque to the Internet, and is only meaningful to
the domain specified by the domain part.  This concept has two modes
based on the sig-type: the first mode uses a secret symmetric key so
validation is only done by the domain in the domain-part of the
address, and the second mode uses a public key so that receivers may
verify the address with public key management being done via domain
keys.

Many participants questioned the need for standardization since it
could be done unilaterally (without coordination of the rest of the
Internet).  Dave noted that even in the first mode, there may be
multiple software components using this validation.  He also noted
that the first mode stops joe-jobs at the destination while the second
mode stops joe-jobs at the source (of injection).

Concerns about replay attacks were mentioned.  Dave suggested that a
timestamp or some other data in the hash may solve the problem.

Many comparisons with other bounce prevention/protection schemes were
raised.  One participant mentioned that Dave's proposal sounded
similar to an old version of the SES proposal.  It was also suggested
that this could best be handled via a BCP rather than a standard.

Item 4: 30% Solution Semantics -- Pete Resnick presenting

Pete presented the "30% Solution": receiving server takes "claimed"
domain name to lookup MARID records describing IP addresses and flags
containing the source (mail- from, ehlo, etc.), flags for legitimacy,
resolution type.  Jim Lyon compared this solution to SPF and
Caller-ID, and noted the similarities.

The group discussed sets of IP addresses as either legitimate,
illegitimate, or unknown.  Subtopics covered deriving the set of
unknown and/or illegitimate from the set of legitimate using set
subtraction, explicit definition of the sets, etc.  Andy asked for a
hum on the need for independently expressing the three sets; there was
a loud hum for it.

Item 5: 40% Solution Semantics -- Pete Resnick presenting

Pete presented his interpretation of the "40% Solution": receiving
server queries type for legitimate, illegitimate, and unknown status
with "claimed" domain, with subsequent lookups on other types if no
data is found.  Many of the participants expressed concern over the
multiple lookups and perceived serial chaining of lookups with respect
to latency.  Many participants did not understand the nature of the
second query with respect to the first.

The group then undertook a discussion on reputation services.  There
was debate about these services being about reputation or
accreditation.  Concern was expressed that the group did not possess
the needed understanding of either reputation or accreditation
services to adequately define either. The group then discussed the
necessity to provide a hint to the reputation service.  It was noted
that a receiver would not outright trust any reputation hint from a
sender, with the counter argument being that it allows receivers to
only make a single reputation/accreditation inquiry if the hinted
service is in the list of used services by the receiver (thus
eliminating queries to multiple services).

A hum was called on the ability to specify a hint which gives a domain
that gives further information with respect to accreditation (and
could be a second record).  A loud hum was heard.

Item 6: CAA Semantics -- Douglas Otis presenting

Doug presented his CAA proposal using SRV records, with follow-on
discussion by the group.  In summary, the input to the process is
EHLO, with outputs being IP addresses, and a bridge mechanism for
2821.MAILFROM if EHLO does not match.

Item 7: CSV Semantics -- Dave Crocker presenting

Dave presented the CSV proposals.  The group discussed his assertion
that HELO/EHLO is "channel-based" while MAIL FROM is "content-based"
(in that it is tied to the sender).  He also briefly discussed
"vouching services".

Item 8: Tagged Addressing -- Sam Silberman presenting

Sam presented issues around tagged addressing.  The group discussed
replay attacks and the affects of a MARID/LMAP solution on forwarding.
Sam suggested that all forwarding be based on an opt-in relationship.
The group then discussed problems with forwarding and LMAP/MARID
solutions.  The presentation ended with Ted Hardie noting that this
working group does not have a charter allowing the breakage of core
email functionality, and that the working group needs to produce an
applicability statement on the problems being solved.

Item 9: Caller-ID and SPF Converged -- Jim Lyon presenting

Jim presented a plan for convergence of SPF and Caller-ID.  This
convergence would merge the differences between 2821 and 2822 identity
checking by using the 2822 header selection algorithm in Caller-ID and
by promoting it back to a 2821 identity through a proposed SMTP
extension called "RFROM" (responsible from).  It was noted that
2821.MAILFROM is currently overloaded and RFROM would provide clarity
while allowing the check to occur before the SMTP DATA command.  There
was some discussion over spammners adapting to RFROM, but Jim
dismissed the concern.

The new proposal would encompass the SPF semantics while using the XML
encoding of Caller-ID.  Jim gave several examples of how this would
work.  There was then some discussion on extension mechanisms and the
necessity to get the semantics for it right.  There was also concern
that the proposal may be too complex and may contain features that are
interesting but not necessary.  Finally, a concern was raised
regarding the number of recursive queries.

Andy asked the room if they found the converged plan valuable and wise
use of time and received a loud hum.

Item 10: CSV Semantics Continued -- Dave Crocker presenting
Link - http://brandenburg.com/presentations/CSV-Summary.ppt //TODO: update

Dave Crocker continued his presentation from the previous day on CSV,
and explained the cut between the various CSV drafts.  Dave's main
point is that CSV is orthogonal to the SPF and Caller-ID solutions,
and that CSV is inherently transitive unlike checks of MAIL FROM.  A
concerned was raised about multiple independent mechanisms.  The group
finished up the discussion with a comparison of the semantics of CSV
with TLS and dial- back schemes.

Item 11: DNS Considerations -- Ed Lewis presenting
Link - http://homepage.mac.com/resnick/copy_MARID-DNS.ppt  //TODO: update

Ed presented various issues with extending DNS based on past attempts.
The group compared the advice to not use naming conventions with the
popular use of SRV records.  Many concluded that if SRV were to be
defined today using this advice, it would not be feasible.  Discussion
also centered around adding a new RR type to DNS.  Ed noted that the
DNS community had previously been very uneasy in defining new record
types for fear of depleting the namespace, but that fear no longer
existed and new record types were considered the appropriate device
for extending DNS.  Many in the room were convince that adding a new
record type to DNS would take 5 years or longer.

The group undertook a long discussion regarding client DNS support.
Some in the room felt that the issue should not sway the adoption of a
new record type because it was relatively simple to write UDP DNS
clients (one participant pointed out that most malware has its own
simple code for this function).  However, most of the participants in
the room felt that DNS client support was lacking.  One participant
pointed to a vendor solution that used RPC instead of DNS in certain
situations.

The participants then discussed wildcards.  It was noted that the
"name hack" excluded the use of wildcards without new DNS server code.
Using SOA records to determine zone cuts for the purposes of
tree-walking was also discussed.  Ed questioned the viability of such
an algorithm.

Andy asked for a hum of the room regarding the desire for a
"wildcard-like" function and received a hum in favor of it.


Item 12: Utility of Bounce Addresses -- Pete Resnick presenting

Pete started a discussion on bounces being tossed on the Internet by
convention.  This brought back many points for earlier discussions
such as comparison of proposals using the EHLO banner for checking and
the themes around tagged bounce address validation.

Item 13: Action Items -- Marshall Rose presiding

Action 1 -- Harry Katz, Jim Lyon and Meng Wong are to develop a
schedule for the output of the SPF/Caller-ID converged drafts and send
it to the list.

Action 2 -- All parties are to review IPR disclosures with respect to
their proposal.

Action 3 -- Dave Crocker and Doug Otis are to develop a schedule for
the output of CSV/CAA/SRV related drafts.

Action 4 -- Daniel Quinlan to write a draft to standardize the
Received header format, and mention RFROM.


<Prev in Thread] Current Thread [Next in Thread>