Re: [OPSEC] I-D Action: draft-ietf-opsec-ipv6-eh-filtering-07.txt

Fernando Gont <fgont@si6networks.com> Sun, 24 January 2021 05:45 UTC

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From: Fernando Gont <fgont@si6networks.com>
To: Michael Dougherty <jerniman@jernilan.net>, "opsec@ietf.org" <opsec@ietf.org>
Cc: "liushucheng@huawei.com" <liushucheng@huawei.com>
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Date: Sun, 24 Jan 2021 02:42:24 -0300
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Subject: Re: [OPSEC] I-D Action: draft-ietf-opsec-ipv6-eh-filtering-07.txt
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Hello, Michael,

Thanks a lot for your input! In-line...

On 20/1/21 22:31, Michael Dougherty wrote:
> Greetings,
> 
> This was an interesting topic and write up. I have a few comments
> related to writing structure and readability.
> 
> Original: While some operators "officially" drop packets that contain
> IPv6 EHs, it is possible that some of the measured packet drops be
> the result of improper configuration defaults, or inappropriate
> advice in this area.
> 
> Suggestion: While some operators "officially" drop packets that
> contain IPv6 EHs; it is possible that some of the measured packet
> drops be the result of improper configuration defaults, or
> inappropriate advice in this area.

Wouldn't the s/,/;/ make the two sentences more unrelated, when they are 
actually meant to be closely-related?


> Original: The advice in this document is aimed only at transit
> routers that may need to enforce a filtering policy based on the EHs
> and IPv6 options a packet may contain, following a "deny-list"
> approach, and hence is likely to be much more permissive that a
> filtering policy to be employed at e.g. the edge of an enterprise
> network.
> 
> Suggestion: The advice in this document is aimed only at transit
> routers that may need to enforce a filtering policy based on the EHs
> and IPv6 options a packet may contain, following a "deny-list"
> approach, and hence is likely to be much more permissive than a
> filtering policy to be employed at, e.g., the edge of an enterprise
> network.

Will do!


> 
> Original: Section 4.2, first paragraph, second sentence Essentially,
> packets that contain IPv6 options might need to be processed by an
> IPv6 router's general-purpose CPU,and hence could present a DDoS risk
> to that router's general-purpose CPU (and thus to the router
> itself).
> 
> Suggestion: Essentially, packets that contain IPv6 options that might
> need to be processed by an IPv6 router's general-purpose CPU and
> could present a DDoS risk to that router's general-purpose CPU.

Will do.


> 
> Comments: 1 - Within the last sentence of the third paragraph within
> the "Introduction" sections. There is a comment about "inappropriate
> and missing guidelines". Who dictates or decides what is
> inappropriate?

Well, that's indeed subjective. One might say that, for example, "drop 
all packets with EHs (regarding the EH-chain length) at transit routers" 
is probably inappropriate.

That said, if you have any suggested tweaks, please do let us know (I'm 
all for improving the document).


> 2 - First bullet point in Section 2.3, change
> "recognise" to "recognize" 3

Will do.


> - Within the last paragraph of section
> 2.3, part of the comment ".... it is generally desirable that the
> sender be signaled of the packet drop...." While the idea is valid,
> it might be a good idea to note that such a signal might attract
> malicious attention or threat-actors.

You mean "expose the filtering policy"? If not, please elaborate. :-)


> 4 - Section 3.4.4.4. It might
> be best to specify what type of IPSEC deployment is involved,
> host-to-host, site-to-site, site-to-host? 

Could you please elaborate a bit on this one?



> 5 - Section 3.4.5.5.
> Advise, hasn't AH been depreciated as an insecure methodology versus
> ESP?

That'd generally be my take. But AH has never been formally obsoleted. 
While double-checking this, I ended up finding this thread 
(http://www.sandelman.ottawa.on.ca/ipsec/2000/06/threads.html#00063 ) in 
which some folks have actually suggested that, but it looks like the 
idea didn't fly.

Thanks!

Regards,
-- 
Fernando Gont
SI6 Networks
e-mail: fgont@si6networks.com
PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492