[Gen-art] Re: Gen-ART review of draft-ietf-v6ops-ipsec-tunnels-04.txt

[[e-mail]]

Sorry for the lack of subject in the first one (stupid Outlook
stunt), here it is with a subject.  FYI, --David

> -----Original Message-----
> From: [e-mail] [mailto:[e-mail]] 
> Sent: Thursday, January 18, 2007 10:31 AM
> To: [e-mail]
> Cc: [e-mail]; [e-mail]; 
> [e-mail]; [e-mail]; 
> [e-mail]; [e-mail]; [e-mail]
> Subject: [Gen-art] (no subject)
> 
> Pekka and Brian,
> 
> The -05 version is much better - it's sufficiently improved to remove
> the Discuss in the draft's current form.  Nonetheless, I 
> suggest that an
> RFC Editor note be used to insert the following text (much of which
> Fred Baker wrote) to explain what "modeled as an interface" means:
> 
>   An important consideration in determining whether to use 
> IPsec tunnel
>   mode is whether the IPsec tunnel mode SA is modeled as an interface.
>   This notion of interface is logical - any time a system, host or
>   router, sends a datagram, it has to account for having done so using
>   the RFC 2863 Interface MIB.  To do so, the system derives 
> ifIndex from
>   the route entry (see InetCidrRouteEntry in RFC 4292) that it uses to
>   forward the   datagram, or from the IpDefaultRouterEntry described
>   in RFC 4293.  The management information accessed via the ifIndex
>   is "the interface" from a management and configuration perspective.
> 
> This text should be inserted immediately following this sentence in
> Section 5:
> 
>   The IPv6 traffic can be protected using transport or tunnel mode.
> 
> This will also entail adding informative references to RFCs 2863,
> 4292 and 4293.  This is close to the limit of what I'd be comfortable
> doing with an RFC Editor Note, but I think this would significantly
> improve the clarity of the "what is an interface?" confusion that
> I stumbled over in the original review.
> 
> Thanks,
> --David
> ----------------------------------------------------
> David L. Black, Senior Technologist
> EMC Corporation, 176 South St., Hopkinton, MA  01748
> [phone]             FAX: [phone]
> [e-mail]        Mobile: [phone]
> ----------------------------------------------------
> 
> > -----Original Message-----
> > From: Pekka Savola [mailto:[e-mail]] 
> > Sent: Thursday, January 18, 2007 3:11 AM
> > To: Black, David
> > Cc: [e-mail]; [e-mail]; [e-mail]; 
> > [e-mail]; [e-mail]; 
> > [e-mail]; [e-mail]
> > Subject: Re: Gen-ART review of draft-ietf-v6ops-ipsec-tunnels-04.txt
> > 
> > Hello David (B.), Brian,
> > 
> > A new version of the draft has been submitted.  We believe it 
> > addresses 
> > your comments.  Please check it out.  This was the only DISCUSS.
> > 
> > http://tools.ietf.org/wg/v6ops/draft-ietf-v6ops-ipsec-tunnels/
> > 
> > Below are a few notes where it isn't 100% clear whether the 
> > desired impact 
> > was achieved.
> > 
> >   - section 5.0 almost in its entirety (most text moved from 
> > deleted section 5.2).
> > 
> >   NOTE: I think section 5 is still a bit unclear of when 
> > "interface" refers
> >   to "IP interface" and when "tunnel interface".
> > 
> >   NOTE: we also now explicitly state that ingress filtering 
> > configuration 
> > must be applied manually [it cannot be negotiated as part of 
> > IKE or IPsec 
> > configuration, for example].  This is likely good enough, 
> but I think 
> > David Black was looking for a bit more than that -- 
> unfortunately, I 
> > don't think any IPsec-side automation can be provided..
> > 
> > On Sat, 9 Dec 2006 [e-mail] wrote:
> > > I have been selected as the General Area Review Team (Gen-ART)
> > > reviewer for this draft (for background on Gen-ART, please see
> > > http://www.alvestrand.no/ietf/gen/art/gen-art-FAQ.html).
> > >
> > > Please wait for direction from your document shepherd
> > > or AD before posting a new version of the draft.
> > >
> > > Document: draft-ietf-v6ops-ipsec-tunnels-04.txt
> > > Reviewer: David L. Black
> > > Review Date: 9 December 2006
> > > IESG Telechat date: 14 December 2006
> > >
> > > Summary:
> > >
> > > This draft is on the right track, but has open issues, described
> > > in the review.
> > >
> > > Comments:
> > >
> > > As an informational document whose primary purpose is to 
> explain how
> > > to use protocols specified elsewhere, clarity is of primary
> importance.
> > > While I was able to figure out what the draft is trying to say, it
> > > needs attention.
> > >
> > > The open issues include the clarity problems in Section 4 
> that rise
> to
> > > the level of possible or actual technical misstatements, 
> the lack of
> > > explanation of requirements in Section 5.2, and the missing IPsec
> > > details.
> > >
> > > My detailed comments are as follows:
> > >
> > > The recommendation against tunnel mode should be included in the
> > > abstract.
> > >
> > > Section 4 has some wording problems:
> > >
> > >   1.  [RFC2401] does not allow IP as the next layer protocol in
> traffic
> > >       selectors when an IPsec SA is negotiated.  [RFC4301] also
> allows
> > >       IP as the next layer protocol (like TCP or UDP) in traffic
> > >       selectors.
> > >
> > > The "also" is susceptible to misreading.  The second 
> sentence should
> > > be rephrased to: "In contrast, [RFC4301] does allow ..."
> > >
> > >   2.  [RFC4301] assumes IKEv2, as some of the new 
> features cannot be
> > >       negotiated using IKEv1.  It is valid to negotiate multiple
> > >       traffic selectors for a given IPsec SA in 
> [RFC4301].  This is
> > >       possible only with [RFC4306].  If [RFC2409] is used, then
> > >       multiple SAs need to be set up for each traffic selector.
> > >
> > > The last sentence is incorrect as written ("set up" needs to be
> > > replaces by "set up, one for each" to correct it) and the use of
> > > RFC numbers for protocol names is semi-opaque.  The 
> following would
> > > be much clearer:
> > >
> > >   2.  [RFC4301] assumes IKEv2, as some of the new 
> features cannot be
> > >       negotiated using IKEv1.  It is valid to negotiate multiple
> > >       traffic selectors for a given IPsec SA in 
> [RFC4301].  This is
> > >       possible only with IKEv2.  If IKEv1 is used as specified in
> > >       [RFC2409], then each traffic selector requires a 
> separate SA.
> > >
> > > I strongly recommend use of the protocol names instead of just RFC
> > > numbers for clarity throughout the draft, and using both (e.g.,
> > > "IKEv1 [RFC2409]") is an acceptable alternative.
> > >
> > > Table 1 in Section 5 uses acronyms for addresses in the "Contains"
> > > column that need to be defined before they are used.
> > >
> > > Section 5.2 discusses the consequences of whether the endpoint
> > > of an IPsec tunnel-mode SA is modeled as an IPv6 interface or
> > > not.  It should say that there is always an IPv6 interface at
> > > the endpoint of a IPv6-in-IPv4 tunnel, and the discussion of
> > > whether to model the SA as an interface is concerned with
> > > whether the functionality of an IPv6 interface is realized by
> > > the IPsec SA or outside of it.
> > >
> > > It should also be stated that all uses of the word "interface"
> > > refer to an IPv6 interface, and that the phrase "tunnel interface"
> > > refers to an IPv6 interface at the endpoint of an IPv6-in-IPv4
> > > tunnel, independent of whether the tunnel is realized by IPsec
> > > tunnel mode.  The end of Section 1 would be a good place to
> > > do this.  The use of the phrase "IP interface" in Section A.1
> > > is considerably clearer than the use of "interface" without "IP"
> > > in Section 5.2 - using "IP interface" throughout Section 5.2
> > > (and for that matter the entire draft) would improve readability.
> > >
> > > The three requirements in Section 5.2 are generally applicable,
> > > and should not be buried in Section 5.2's discussion of IPsec
> > > tunnel mode.  The requirements also lack explanations of why
> > > they are requirements.  At a minimum, the statement of the
> > > requirements should be moved into Section 5 (before 5.1), but
> > > I would suggest moving them to the end of Section 3 and adding
> > > a discussion of why these requirements are important (e.g., what
> > > goes wrong if they're not met) with reference to the scenarios
> > > described in Section 3.
> > >
> > > Cross-checking this draft against the elements in Section 8
> > > of draft-bellovin-useipsec-05.txt, I find some things that need
> > > attention:
> > > 	a) Selectors - Yes, specified in Section 5.1
> > > 	b) IPsec protocol and mode - Yes, ESP vs. AH is at the
> > > 		end of section 4 and tunnel-vs-transport is a
> > > 		major portion of this draft.
> > > 	c) Key management - Almost.  The numerous mentions of
> > > 		IKE indicate a preference for automatic keying, but
> > > 		there should also be a strong recommendation against
> > > 		manual keying, due to the amount of IPv6 traffic that
> > > 		may use an IPv6-in-IPv4 tunnel.  Manual keying of
> > > 		IKE needs to be clearly distinguished from manual
> > > 		configuration of the IPv6-in-IPv4 tunnel.  The end
> > > 		of Section 2 would be a good location for these topics.
> > > 	d) SPD entries - Yes, specified in Section 5.1
> > > 	e) Identification forms - Yes, but.  The first bullet in
> > > 		Section 5.3 has a weak recommendation for IPv4
> > > 		addresses as identities.  The "but" is that ingress
> > > 		filtering is discussed entirely in the abstract, and
> > > 		additional discussion is needed about how to determine
> > > 		what IPv6 ingress filter to use with which IPv4 address
> > > 		(this may be part of tunnel configuration).
> > > 	f) Authentication form - Yes, second bullet in section 5.3
> > > 	g) IKE versions and modes - No.  Section 4 implies that
> > > 		both IKEv1 and IKEv2 can be used, although IKEv2 is
> > > 		somewhat preferred - this should probably be stated
> > > 		explicitly.  There is no discussion of IKEv1 Main vs.
> > > 		Aggressive mode - it would suffice to say that if
> > > 		IPv4 addresses are used as identities, identity
> > > 		protection is not required (it's obvious where the
> > > 		traffic is coming from), making Aggressive mode an
> > > 		acceptable alternative to Main mode.
> > > 	h) IPsec support availability - No.  This can be side-
> > > 		stepped to some extent by noting that the IPv6 RFCs
> > > 		require IPsec support.
> > >
> > > Note that I am not asking that this draft meet all the 
> requirements
> > > in Section 8 of the bellovin-useipsec draft, and in 
> particular, I'm
> > > giving this draft significant slack against the usual IETF
> > > requirement that sufficient mandatory-to-implement elements be
> > > specified for interoperability.  With the possible exception of
> > > IKEv1 vs. IKEv2, interoperability requirements belong in the RFCs
> > > that specify the protocols involved.
> > >
> > > Thanks,
> > > --David
> > > ----------------------------------------------------
> > > David L. Black, Senior Technologist
> > > EMC Corporation, 176 South St., Hopkinton, MA  01748
> > > [phone]             FAX: [phone]
> > > [e-mail]        Mobile: [phone]
> > > ----------------------------------------------------
> 
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