Re: [5gangip] [Ila] ILA forwaring [Was Re: Problem Statement]

[Tom Herbert <[e-mail]>]

On Thu, May 3, 2018 at 11:52 AM, Behcet Sarikaya <[e-mail]> wrote:
>
>
> On Thu, May 3, 2018 at 12:46 PM, Tom Herbert <[e-mail]> wrote:
>>
>> On Thu, May 3, 2018 at 9:23 AM,  <[e-mail]> wrote:
>> > Hi Tom,
>> > I understand you correctly that DDOS attacks can never be completely
>> > prevented whatever protocol you use.
>> > It will however always remain related to known IP addresses and the more
>> > versatile these are handled a mitigation strategy could be designed.
>>
>> Dirk,
>>
>> I disagree. IP addresses can too easily be spoofed, it's easy to hide
>> identity behind a NAT (see discussion about CGNAT and law enforcement
>> on int-area list), and trying to turn off individual addresses doesn't
>> work if it's a DDOS. This is nothing new. For instance, content
>> providers have long accepted the fact that they can't prevent SYN
>> attacks and there's little point to trying to go back to source IP
>> address (they are always spoofed in a SYN attack). The better strategy
>> is to absorb the attack and minimize the negative effects so that the
>> attack is not worth the effort.
>>
>> > As you may have seen we mention improved handling of mapping systems and
>> > subsequently of DDOS protection also in the current version of our PS
>> > document
>> > https://github.com/bsarikaya/atic/blob/master/atick_problemstatement.3.txt
>> > which Behcet has announced recently.
>> > May I ask you to please comment on the ideas outlined there?
>>
>
>
>>
>> I don't see much difference in the latest version.
>
>
> Really?
>
>>
>> For a problem
>> statement, I still think there is too much focus on the solutions
>
>

Hi Behcet,

> You mean ILA, ILNP and LISP are solutions and PS draft talks a lot about
> them?
>
Yes.

>>
>> and
>> not nearly enough description of what the actual problems are to be
>> solved.
>>
>
> I appreciate this comment but I don't get how we can remedy it.
> Can you please give some hints on what you want to see in the document and
> in what order?
>
Offhand, I'd say that these are some problems of mapping systems or
problems that might be addressed by mapping sytems:

- If addresses (or device prefixes) are common between flows then a
third party can make inferences (i.e. whether they're sourced from the
same host). This gets into the problems of persistent identifiers.
This was touched upon indirectly in IDEAS with discussions about
identity.
- If addresses contain fine grained topology then device location (and
hence user location can be inferred). This
gets to the problem that locators may very contain geographic location
and hence are very sensistive data.
- If a cache is introduced into the data path (as might be the case in
some mapping systems) then that in turn will introduce potential DOS
attacks.
- Compromise of a mapping system is very bad since it would allow
attackers to misdirect (I believe there was recently an incident where
someone managed to spoof BGP to take control of traffic.
- More generally, what is the real problem is really being solved?

Draft says:

"In addition to increasing packet overhead due to encapsulation that
may cause fragmentation and all related issues typical disadvantages
of (especially static end-to-end) tunneling comprise inflexibility to
properly react to dynamic changes of end points and potential on-path
anchors."

That's a bit misleading since not all Mapping Systems avoid
encapsulation or tunneling. I believe that the primary benefits are
elimination of reduction of anchor points, as well as disassciating
topology from IP addressess to facilitate efficient mobility and user
privacy..

Tom

> Maybe the first paragraph can be restructured to state the current problem
> first and then mention proposed solutions?
>
> We can do that.
> In the following paragraphs we continue with each ID-Loc system and try to
> describe the common problem of privacy based mapping system.
>
> I'll appreciate if you could tell how you would restructure it?
>
> Of course the same question to others who already comments or not, please
> speak up!
>
>
> Thanks,
> Behcet
>
>>
>> Tom
>>
>> > Thanks!
>>
>> > Best Regards
>> > Dirk
>> >
>> > -----Original Message-----
>> > From: 5gangip [mailto:[e-mail]] On Behalf Of Tom Herbert
>> > Sent: Mittwoch, 2. Mai 2018 01:20
>> > To: Joel M. Halpern <[e-mail]>
>> > Cc: Tom Herbert <[e-mail]>; [e-mail]; Alberto
>> > Rodriguez-Natal <[e-mail]>; 5GANGIP <[e-mail]>
>> > Subject: Re: [5gangip] [Ila] ILA forwaring [Was Re: Problem Statement]
>> >
>> > On Tue, May 1, 2018 at 3:49 PM, Joel M. Halpern <[e-mail]>
>> > wrote:
>> >> You seem to be saying that even though not all DDOS attacks are
>> >> structurally the same, and even though if ILA were widely adopted not
>> >> all ILA networks would be structurally the same, there should
>> >> nonetheless be one required qay of handling DDOS?
>> >
>> > Yes, at least as core default in the protocol. It's precisely _because_
>> > not all DDOS attacks are structurally the same. An attacker is not going to
>> > conform to to our expectations of what they should be doing, so if we enable
>> > LISP option N to mitigate one form of attack, they will just use another
>> > attack that isn't mitigated. For example, if the mitigation is to identify
>> > attackers by address when requests from the address exceed a threshold then
>> > this works as long as the attacker strikes from one machine, but it falls
>> > apart if the attacker launches a DDOS attack from several hosts where
>> > requests from none of the hosts exceed the threshold.
>> >
>> > The ILA model works because it assumes there is no absolute way to
>> > prevent the the worst case attack on a cache which is to completely kill it
>> > (i..e. drive it to 0% hit rate). In this state the behavior sub-optimal
>> > routing, which is much better than loss of service. This is not dependent on
>> > the structure of the attack, network topology, or the network operator
>> > getting the configuration just right-- it is inherent in the protocol.
>>
>> >
>> > Tom
>> >
>> >>
>> >> Yours,
>> >> Joel
>> >>
>> >>
>> >> On 5/1/18 6:32 PM, Tom Herbert wrote:
>> >>>
>> >>> On Tue, May 1, 2018 at 2:59 PM, Alberto Rodriguez-Natal
>> >>> <[e-mail]> wrote:
>> >>>>
>> >>>> On Tue, May 1, 2018 at 10:16 AM, Tom Herbert <[e-mail]>
>> >>>> wrote:
>> >>>>>
>> >>>>>
>> >>>>> I think you've misunderstood my position. Caches are _very_
>> >>>>> important to eliminate the cost triangular routing (latency, average
>> >>>>> path load).
>> >>>>> This reduces latency and reduces average load on ILA-Rs. But, and
>> >>>>> this is the critical part, caches are only an _optimization_ in
>> >>>>> ILA. That means if the cache is rendered ineffective (like by a
>> >>>>> well crafted DOS
>> >>>>> attack) then the only effect is that the optimization is loss (i.e.
>> >>>>> greater latency due to triangular router)-- this is quantitively
>> >>>>> the worst effect of the attack on an ILA cache. This can be
>> >>>>> contrasted that to LISP where the worst case effects of a DOS
>> >>>>> attack on the cache is loss of service for users (infinite latency
>> >>>>> since packets can be dropped or indefinitely blocked on a cache
>> >>>>> miss).
>> >>>>
>> >>>>
>> >>>>
>> >>>> This can be misleading. This is not comparing LISP vs ILA, this is
>> >>>> comparing the models of Request/Reply at the edge vs Notifications
>> >>>> (aka Redirects) at the core. Both LISP-CP and ILAMP support these
>> >>>> two models.
>> >>>>
>> >>>> Besides, this is assuming an scenario where the only feasible DOS
>> >>>> mitigation is absorbing the attack. There are other scenarios where
>> >>>> other countermeasures are possible. For instance, if you have a
>> >>>> deployment where you can prevent address spoofing, counting and
>> >>>> blocking misbehaving nodes offers similar DOS protection and
>> >>>> requires way less infrastructure resources.
>> >>>>
>> >>> Alberto,
>> >>>
>> >>> The answer to my question of how does LISP address DOS attacks seems
>> >>> to be "there are many options". Some of the options are to assume
>> >>> that DOS does not exist in the network, some assume external
>> >>> configuration like address spoofing is enabled, some assume that
>> >>> attacks can be identified and can be stopped at the source, some
>> >>> might assume that everything is okay because there's never been a DOS
>> >>> attack before. I have yet to see the effects of any of these
>> >>> quantified, and none of these state how the LISP _protocol_ itself
>> >>> addresses DOS. It may seem counter-intuitive, but offering a bunch of
>> >>> options really is not necessarily a good thing-- sometime less is
>> >>> more. To put this another way LISP has been rejected from Linux
>> >>> precisely because of its susceptibility to DOS. If you were to try
>> >>> again and the best answer to the DOS question is that it's up to the
>> >>> operator to figure out the right options to use, then I believe it
>> >>> would be soundly rejected again. That approach does not work at scale.
>> >>>
>> >>> Tom
>> >>>
>> >>> _______________________________________________
>> >>> ila mailing list
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>> >>> https://www.ietf.org/mailman/listinfo/ila
>> >>>
>> >>
>> >
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