NAT etc. (was: Spam Control Considered Harmful)

Sat Nov 1 20:34:13 UTC 1997

[ I just removed these addresses:

  Havard.Eidnes at runit.sintef.no
  smd at clock.org
  peter at wonderland.org
  jlewis at inorganic5.fdt.net
  paulp at winterlan.com

  ...from the recipient list, since I know they are all on NANOG.  I would
  not be offended by each of the above people thanking me publically for
  not making them see two copies of this reply.  Perhaps that would set
  some kind of an example for the rest of the audience, most of whom just
  say "reply-all". ]

Havard said:

> ...which brings me to think if it isn't so that Secure DNS (at
> least as currently specified) and widespread deployment of NAT
> boxes which fiddle with the contents of DNS reply/request packets
> isn't exactly a properly working combination.  As I understand it
> you can have NAT or Secure DNS with e.g. signed A records but you
> can't (easily?) have both.

This is a misdirected concern.  DNS clients inside a NAT cloud are
already proscribed from seeing DNS data from other NAT clouds or from
the Internet itself.  The NAT technology has to strip off DNSSEC stuff
when it imports data but it tends to strip off DNS delegation and
authority data as well, and tends to alter the address and mail exchange
records.  NAT borders are already DNS endpoints, with or without DNSSEC.
Whether and how to regenerate external DNS inside a NAT cloud is a matter
of NAT implementation, but the fact that it's _regenerated_, not forwarded
or recursed, is a design constant.