Hi Joel,
The proposal is not to restrict the usage of PubSub to “limited
domains” as per RFC8799. Please refer to
https://github.com/boucadair/draft-ietf-lisp-pubsub/pull/16/files to
see the text we are planning to include as applicability scope.
I think this is a reasonable suggestion especially that we want to
leverage 9301/9303.
Thank you.
Cheers,
Med
*De :*Joel Halpern <[email protected]>
*Envoyé :* mercredi 15 février 2023 17:32
*À :* BOUCADAIR Mohamed INNOV/NET <[email protected]>;
Magnus Westerlund <[email protected]>; Alberto
Rodriguez-Natal (natal) <[email protected]>; [email protected]
*Cc :* [email protected]; [email protected];
[email protected]
*Objet :* Re: [lisp] Tsvart last call review of draft-ietf-lisp-pubsub-10
Hmmm.
Maybe I misunderstood, but a lot of the uses I have seen for the
pub-sub mechanism do not seem to be limited enough to qualify for
being a limited domain.
On the other hand, the general idea of the DDOS prevention mechanism
(modeled loosely on the prevention of TCP State attacks) seems
valuable and easy to add. If a Map Server serving a broad community
gets a pub-sub subscription request, and it is under any significant
load, it can
1) craft a security token hashing the request, the current time, and a
private key (and whatever else security says is needed
2) Sending the token and time back to the requestor in an error
3) When the requestor sends back the request, it includes the
timestamp and token. The server only processes the request if the
information validates.
This validates that the response actually went to the requestor, and
was a real request. Yes, it slightly slows down the pub-sub
registration under load.
I don't know if I caught all of Magnus' issue, but this would seem a
good thing to do.
Yours,
Joel
On 2/15/2023 3:24 AM, [email protected] wrote:
Hi Magnus,
Thank you for the follow-up.
First, your observation on the verification procedure at the
Map-Server is fair. We have documented the issue in
draft-boucadair-lisp-pubsub-flow-examples-03.html#name-failed-notification-with-ret
<https://www.ietf.org/archive/id/draft-boucadair-lisp-pubsub-flow-examples-03.html#name-failed-notification-with-ret>
and discussed the alternative to strengthen the verification based
on the timestamp but we had also the constraint to navigate in the
LISP environment where LISP-SEC messages are not timestamped. We
think that the procedure in the draft is a good compromise of what
we can achieve given that constraint. FWIW, the full reasoning is
available at: timestamp to prevent replay attacks · Issue #1 ·
boucadair/draft-ietf-lisp-pubsub (github.com)
<https://github.com/boucadair/draft-ietf-lisp-pubsub/issues/1>.
Second, I support your proposal to add an applicability statement
to the document. The content will be basically moving (and
adjusting the language) the following text in Section 7 to that
section:
OLD:
It is also RECOMMENDED that the Map-Resolver
verifies that the xTR is allowed to use PubSub and to use the
xTR-ID
and ITR-RLOCs included in the Map-Request. Map-Servers SHOULD be
configured to only accept subscription requests from Map-Resolvers
that verify Map-Requests as previously described.
I let Alberto further comment as appropriate.
Cheers,
Med
*De :*Magnus Westerlund <[email protected]>
<mailto:[email protected]>
*Envoyé :* mercredi 15 février 2023 08:33
*À :* Alberto Rodriguez-Natal (natal) <[email protected]>
<mailto:[email protected]>; BOUCADAIR Mohamed INNOV/NET
<[email protected]>
<mailto:[email protected]>; [email protected]
*Cc :* [email protected]; [email protected];
[email protected]
*Objet :* Re: Tsvart last call review of draft-ietf-lisp-pubsub-10
Hi,
Thanks for the many improvements and I think this is likely safe
enough for limited deployments when the Map-Server are not open to
any xTR to send requests. I don’t think this is safe enough for
general Internet usage for two reasons. First, the verification
procedure forces the MAP-Server to hold state rather than the
requestor and the messages only. Secondly, a lot of the security
procedures are only RECOMMEND/SHOULD. For an open Internet I think
a more tightly defined security mechanisms and protection profile
should be specified.
Thus, my recommendation would be to add an applicability statement
to the document making clear that this is intended for the
deployments with more limited access to Map-Servers than what an
open internet deployment provides.
Cheers
Magnus Westerlund
*From: *Alberto Rodriguez-Natal (natal) <[email protected]>
*Date: *Monday, 13 February 2023 at 20:26
*To: *[email protected] <[email protected]>,
Magnus Westerlund <[email protected]>,
[email protected] <[email protected]>
*Cc: *[email protected]
<[email protected]>, [email protected]
<[email protected]>, [email protected] <[email protected]>
*Subject: *Re: Tsvart last call review of draft-ietf-lisp-pubsub-10
Hi Magnus,
Just FYI, we have just published a new revision that further
polishes some details.
https://datatracker.ietf.org/doc/html/draft-ietf-lisp-pubsub-12
https://author-tools.ietf.org/iddiff?url2=draft-ietf-lisp-pubsub-12
Thanks!
Alberto
*From: *[email protected] <[email protected]>
*Date: *Friday, February 10, 2023 at 3:55 PM
*To: *Magnus Westerlund <[email protected]>, Alberto
Rodriguez-Natal (natal) <[email protected]>, [email protected]
<[email protected]>
*Cc: *[email protected]
<[email protected]>, [email protected]
<[email protected]>, [email protected] <[email protected]>
*Subject: *RE: Tsvart last call review of draft-ietf-lisp-pubsub-10
Hi Magnus,
FWIW, an updated version that implements the changes that were
discussed in this thread is now online:
https://author-tools.ietf.org/iddiff?url2=draft-ietf-lisp-pubsub-11
<https://author-tools.ietf.org/iddiff?url2=draft-ietf-lisp-pubsub-11>
Cheers,
Med
*De :*BOUCADAIR Mohamed INNOV/NET
*Envoyé :* mardi 7 février 2023 13:15
*À :* 'Magnus Westerlund' <[email protected]>;
Alberto Rodriguez-Natal (natal) <[email protected]>; [email protected]
*Cc :* [email protected]; [email protected];
[email protected]
*Objet :* RE: Tsvart last call review of draft-ietf-lisp-pubsub-10
Hi Magnus,
Thanks for the follow-up.
Please see inline.
Cheers,
Med
*De :*Magnus Westerlund <[email protected]>
*Envoyé :* vendredi 3 février 2023 10:49
*À :* BOUCADAIR Mohamed INNOV/NET <[email protected]>;
Alberto Rodriguez-Natal (natal) <[email protected]>; [email protected]
*Cc :* [email protected]; [email protected];
[email protected]
*Objet :* Re: Tsvart last call review of draft-ietf-lisp-pubsub-10
Hi Med,
Thanks, so that at least you can have a clear notification of the
removal unless the packet loss rate is to high. What, is less
ideal is the number of total messages that is going to be sent
here towards the source address that sent a Map-Register?
*/[Med] I guess you meant Map-Request. Yes, there is a balance
between the chattiness vs. reverse-routeablity checks and also the
constraints imposed by the base spec for retransmission
Map-Notifies. Having an explicit indication is superior as it
allows an xTR to reinstall the state, otherwise it will be out of
sync. /*
*//*
It would be good to have understanding of the amplification factor
here that an attacker gets out it.
*/[Med] Such attacks assume that a Map-Request passes the
authentication checks. This is typically the case of replayed
Map-Requests. As you can see in
https://datatracker.ietf.org/doc/draft-boucadair-lisp-pubsub-flow-examples/,
a check based on the nonce would be sufficient to detect replayed
messages: the nonce has to be greater than the local one. The
message will be then silently ignored. We will be adding more
details about nonce checks to the draft./*
*//*
Also beyond rate limiting, is there a possibility here to reject
the MAP-requests from a source address, without causing a denial
of service attack possibility? My shallow review seem to indicate
that there exist such a risk. What I am considering is that there
is a legit xTR (B) with IP (IP-B). If the attacker sends a
MAP-Request with nonce-A, with IP source address IP-B.
*/[Med] If the nonce checks are in place, this request will be
silently discarded./*
*//*
The Map-Notify will go to B. B can’t map this to a request it made
as no Nonce matches what it sends and discards the message. Thus,
the map server getting a mix of legit and spoofed requests may
decide to band IP-B from asking things, thus enabling a denial of
service on B.
The above worries me a bit as some mitigation may have really
unwanted effects here.
Cheers
Magnus
*From: *[email protected] <[email protected]>
*Date: *Monday, 30 January 2023 at 13:45
*To: *Alberto Rodriguez-Natal (natal) <[email protected]>, Magnus
Westerlund <[email protected]>, [email protected]
<[email protected]>
*Cc: *[email protected]
<[email protected]>, [email protected]
<[email protected]>, [email protected] <[email protected]>
*Subject: *RE: Tsvart last call review of draft-ietf-lisp-pubsub-10
Re-,
Please see inline.
Cheers,
Med
> -----Message d'origine-----
> De : Alberto Rodriguez-Natal (natal) <[email protected]>
> Envoyé : lundi 30 janvier 2023 12:27
> À : Magnus Westerlund <[email protected]>; tsv-
> [email protected]
> Cc : [email protected]; [email protected];
> [email protected]
> Objet : Re: Tsvart last call review of draft-ietf-lisp-pubsub-10
>
> Hi Magnus,
>
> Thanks again, please see inline.
>
> Alberto
>
> From: Magnus Westerlund <[email protected]>
> Date: Monday, January 30, 2023 at 9:46 AM
> To: Alberto Rodriguez-Natal (natal) <[email protected]>, tsv-
> [email protected] <[email protected]>
> Cc: [email protected] <draft-ietf-lisp-
> [email protected]>, [email protected] <[email protected]>,
> [email protected] <[email protected]>
> Subject: Re: Tsvart last call review of draft-ietf-lisp-pubsub-10
> Hi Alberto,
>
> I think the below maybe works, but I like to point out that the
> Map-Server per the below is likely a larger DDoS traffic reflector
> than if you require a one-to-one exchange where each subscription
> request only results in a single response message. Using Map-
> Notify and requiring Ack will result in that at least 3 Map-
> Notifies are being sent.
>
> [AR] Right, but this is required if we want to align with RFC9301,
> afaik.
[Med] ACK. RFC9301 says the following:
A
Map-Notify is retransmitted until a Map-Notify-Ack is received
by the
Map-Server with the same nonce used in the Map-Notify message.
>
> I am also worried about the state uncertainty here. Because if the
> client sends Map-Notify-Ack on a Map-Notify it will think the
> subscription has succeeded, but if that ACK is lost and the
> MapServer has used up all retransmission it will silently remove
> the requested subscription. Is that not an issue?
>
> [AR] I've been thinking about this as well. Maybe some middle
> ground, assuming that xTRs can be authenticated to some extend as
> being discussed in the other email, could be as follows. Rather
> than wait for the Map-Notify-Ack to mark the subscription state as
> completed, we still mark the subscription as complete as soon as
> the Map-Notify is sent. We still wait for the Map-Notify-Ack to be
> received, and if we exhaust all the retransmissions without
> receiving it, we don't remove the subscription, we keep it as
> unacknowledged. However, we only allow the xTR to have a single
> unacknowledged subscription, subsequent subscription requests from
> the same xTR will be denied (i.e. Map-Reply returned) until the
> xTR is able to properly subscribe and acknowledge the previous
> one. Maybe this could work?
>
[Med] Rather than keeping the state, the Map-Server can remove the
unacknowledged subscription with a Map-Notify with AFI = 0. We may
also consider defining a new ACT value so the xTR have a hint
about why the subscription was removed.
_________________________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu
ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and
delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
_________________________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu
ce message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and
delete this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
_________________________________________________________________________________________________________________________
Ce message et ses pieces jointes peuvent contenir des informations
confidentielles ou privilegiees et ne doivent donc
pas etre diffuses, exploites ou copies sans autorisation. Si vous avez recu ce
message par erreur, veuillez le signaler
a l'expediteur et le detruire ainsi que les pieces jointes. Les messages
electroniques etant susceptibles d'alteration,
Orange decline toute responsabilite si ce message a ete altere, deforme ou
falsifie. Merci.
This message and its attachments may contain confidential or privileged
information that may be protected by law;
they should not be distributed, used or copied without authorisation.
If you have received this email in error, please notify the sender and delete
this message and its attachments.
As emails may be altered, Orange is not liable for messages that have been
modified, changed or falsified.
Thank you.
