[secdir] Review of draft-ietf-ipsecme-traffic-visibility-11

[Sean Turner <[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.

Document Abstract:

This document describes the Wrapped Encapsulating Security Payload 
(WESP) protocol, which builds on the Encapsulating Security Payload 
(ESP) [RFC4303], and is designed to allow intermediate devices to (1) 
ascertain if data confidentiality is being employed within ESP and if 
not, (2) inspect the IPsec packets for network monitoring and access 
control functions.

I don't have any comments on the technical contents of the ID.

But, I do have a comment w.r.t. the approach.*  It seems to me that what 
you're looking for is an indication early on that the coming packets are 
encrypted or not.  Don't we already have that with the 50/51 value in 
the protocol header (IPv4, IPv6, or Extension) immediately preceding the 
ESP/AH header.  Why don't we use that as the indication, prohibit those 
NULL encryption algorithms, and then we're done?  We don't have to worry 
about implementing this protocol, the heuristics algorithm in the other 
I-D, and we don't have to complicate the adoption of ESP/AH?

spt

* The only rationale I saw was in the 3rd paragraph of the introduction 
that says AH doesn't work in NAT environments.  Is that really the 
entire reason?  I thought we were trying to kill NATS?