Security-AD folks,
Over here in the SIDR WG we've been batting around a problem related
to secure authentication of TCP endpoints, essentially how can we
specify TODAY something to use in implementations of a (we think)
important protocol when the underlying technology we need isn't
available (TCP-AO). Some background:

Looking to close the issue of MD5/TCP-AO/SSH/etc out again, The doc:
<http://tools.ietf.org/wg/sidr/draft-ietf-sidr-rpki-rtr/>

Seems to be stuck on this text:

(From the abstract)
" This document describes a protocol to deliver validated
   prefix origin data to routers over ssh."

or a more in depth version of that text at:
<http://tools.ietf.org/html/draft-ietf-sidr-rpki-rtr-12#section-7>

Essentially there is a need to validate that a cache and a router are
talking to the right opposite entity. The authors and
test-implementors enabled this connection over SSH with a fallback
(for debugging I suppose?) over plain-text TCP originally. For a host
of reasons SSH is now considered overkill and likely detrimental to
the cause.

The WG discussed on-list (in this thread):
<http://www.ietf.org/mail-archive/web/sidr/current/msg02397.html>

and at the in-person meeting in Prague (IETF80) the fact that SSH was
probably overkill. The two endpoints want simply  to authenticate the
other endpoint, transport security isn't required here because the
content in the stream is already encypted. The 2 methods approved
today for use in IETF protocols are:
  o tcp-AO
  o ipsec AH

one deprecated method is available as well:
  o tcp-MD5

Of the two approved methods, AO has no implementations on the routers
(yet), nor server side to speak of, AH is relatively heavy weight and
isn't always available on routers today. Talking to routing equipment
implementors (two vendors) there was a feeling that AO will arrive
shortly while AH is still too complex (for router deployments) and is
not going to be available in all of the platforms which will require
this functionality.

On the server side of the equation there is no support for AO, some
for AH (which is nice actually). In short, we don't have a good
direction or belief that there is going to be one with respect to AO
in the near term.

What options are there for this problem? How can we motivate vendors
with a spec that clearly has problems in implementation (no AO, not
full reach for AH)? Are there folks who are tracking availability of
AO? Could we start with something like:

MAY support authentication of nodes with TCP-MD5
MAY support authentication of nodes with IPSEC-AH
MUST support authentication of nodes with TCP-AO

Or is mentioning TCP-MD5 verboten? Essentially it seems that the WG
has gotten wedged and is looking for some guidance from the Security
Area Directors :)

-chris
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