Subject: Re: [OPSEC] "On Firewalls in Internet Security" (Fwd: New Version Notification for draft-gont-opsawg-firewalls-analysis-00.txt)

From: Fernando Gont <[email-masked]>
Date: Fri, 9 Oct 2015 07:25:53 -0300

Hi, Eric,

Thanks so much for your feedback! Please find my comments in-line....

On 10/05/2015 12:57 PM, Eric Vyncke (evyncke) wrote:
> Fernando, Fred and Paul,
> 
> Sorry for belated reply, here are a couple of comments:
> 
> The title is a little ambiguous IMHO it is "On Firewalls in Security"
> (because they also apply inside an 'intranet') or "On Firewalls in
> Internet Protocol (IP) Security" or "On firewalls and Security of the
> Internet" ?

How about "On Firewalls in Network Security"?

> The introduction looks more like an history, so should perhaps be renamed?

How about splitting the historical part into a stand-alone section
renamed as "Firewalls in the IETF" or the like?

> Terminology section should perhaps appear more like an usual terminology
> section and not as a free-form text?

mm.. I guess that from the current contents we can define "firewall" and
"perimeter"?

> Section 3.2 (end to end principle) is interesting but is a little complex
> to read.

Any suggestions on how to improve the text?

> Section 3.3, unsure whether I am reading it correctly but I don't agree
> with the statement that firewall can protect the (network) infrastructure
> against DoS attack (as hinted by "message volume overwhelms"). Rate
> limiters or DoS scrubbing devices do not qualify as 'firewall' IMHO.

Could you elaborate a bit?  e.g., why wouldn't a rate-limited qualify as
a firewall?

> I think section 3.4 (a good one) rather belongs to section 4 and should
> align the taxonomy.

Yep. Looks like we could move this into the base Section 4. (Or were you
meaning something else?)

> Section 4.1, split the first paragraph in two parts. The second one being
> the example given => to make it clear that the "sessions may never be
> initiated from the outside" belongs to the example only

OK, will do.

> Section 4.1, 2nd paragraph, the word 'testing' has an active tone in my
> (non native) English, why not using a more passive verb such as "inspect"
> or "check" ?

Agreed. Will do.

> Section 4.1, at the risk of appearing as 'purist', I would move the NAT
> section from this section and create one on this topic.

Please let me think about this one. f you have any suggestions regarding
whre in the I-D you'd put such a section, please let me know.

> Section 4.2, or rather the perimeter exists but it very very small : one
> physical link :-) or wider: one logical perimeter without any strict
> geographical boundaries.

Yes. :-)

> Section 4.2, should make it clear that the 'tagging' is required (being
> IEEE 802.1Q VLAN tag or ...),

OK.

> and, the end of the section is rather
> negative on this specific FW.

I see... any hints for improvement?

> Section 4.3, I like it of course :-), and I agree there are now scalable
> algorithm to detect anomalies even with a single node (thanks to
> self-learning :-))

Could you elaborate a bit? :-)

> Section 4.3, "Reputation databases have a bad reputation" is a fun
> sentence :-)

Indeed! :-)

> Section 5, I would also use the words of white and black lists as they are
> well-known. I wonder also why there is a specific section 5.1 without a
> section 5.2? 

Section 5.2 was forthcomming... (will hopefuly be there in version -01
of the I-D)

> I would remove this heading and keep the text. Don't forget
> to mention HTTP 2.0 & works such as QUIC.

Will do.

> Section 6, should also mention that FTP & SIP can be used for dynamic
> ports.

Will do.

> It should also mention/repeat that port 80 is not only about HTTP
> but for many protocols 'tunneled' over HTTP.

Will do.

> Section 6, temporary addresses are indeed annoying in some cases but IP
> addresses can also be spoofed.

What we meant here is that things like IPv6 temporary addresses change
such assumption.

But yes, we should comment on spoofing.

> Should mention anti-spoofing? And/or IPSEC
> AH?

Anti spoofing in terms of RPF, or something else?

> Section 7 is about layer-3/layer-4 'packet filtering' which is a specific
> kind of firewalls while the I-D title appears to be more generic. I
> suggest to keep the section but make title more specific and add some
> introduction sentences to this section.

Good grief! Will do.

> Section 8, kind of repeats a former point... Useful text but should unify
> and at a single location

You mean with Section 4.1?

> Section 10 is of course looking for heated comments from the community...

[FWIW, Section 10 will be split into a different document... such that
the heat happens elsewhere :-) ]

> Here are a couple:
> - wonder whether the IETF could have recommendations for all cases?

Certainly not for all -- but better to have something covered, than
nothing :-)

> Moreover, situation will probably continue to evolve
> - zone-based should also allow ICMP inbound ;-)

.... if they relate to an ongoing session?

> There are also important (IMHO) topics MISSING:
> - more and more traffic are encrypted, good for privacy, bad for firewalls
> as they are blind now and mostly useless

Yes and no.

If you mean TLS, it prevents DPI, but still allows for filtering based
on port numbers...

> - recommendation for NOT BLOCKING traffic over the Internet (except to
> each ISP own infrastructure)?

not blocking which sort of traffic?

> - logging / auditing function is missing (talking about security here)
> - logging of event is missing (talking about operation here)

Do you mean in the recommendations section, or elsewhere?

Thanks so much!

Best regards,
-- 
Fernando Gont
SI6 Networks
e-mail: [email-masked]
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