[secdir] Security review of draft-ietf-tsvwg-behave-requirements-update-06

[Ben Laurie <[e-mail]>]

I have reviewed this document as part of the security directorate's ongoing
effort to review all IETF documents being processed by the IESG. These
comments were written primarily for the benefit of the security area
directors. Document editors and WG chairs should treat these comments just
like any other last call comments.

Summary: ready with issues

This document updates the behavioural requirements for NAT, and as noted in
the very comprehensive (thankyou!) security considerations section,
 introduces at least two requirements that might have security consequences.

The ADs should probably consider whether these new requirements are worth
the additional risk.

Also, "Hosts which require a restricted filtering behavior should enable
security-dedicated features (e.g., access control list (ACL)) either
locally or by soliciting a dedicated security device (e.g., firewall)." is
concerning - how will hosts know that they need to update their policies?

"security-dedicate features" is not very informative - it would be helpful
to explain what new behaviour may need to be counteracted. Looking at
sections 5 and 6, to which this text refers, they appear to make NAT more
restrictive, not less, so its unclear why there might be security impact.

BTW, small typo: "only if packets are to be sen to distinct
destination addresses."
sen -> sent