Hi Rober, Alvaro, and Les,
In general, the use of authentication is incompatible with auto-
configuration as it requires some manual configuration.
-----Original Message-----
From: Les Ginsberg (ginsberg) [mailto:ginsberg(_at_)cisco(_dot_)com]
Sent: Saturday, April 08, 2017 6:44 AM
To: Alvaro Retana (aretana); Robert Sparks; gen-art(_at_)ietf(_dot_)org
Cc: draft-ietf-isis-auto-conf(_dot_)all(_at_)ietf(_dot_)org;
ietf(_at_)ietf(_dot_)org; isis-wg(_at_)ietf(_dot_)org
Subject: RE: Genart last call review of draft-ietf-isis-auto-conf-04
Alvaro -
Not sure how long we should debate this as the text you are asking for is
modest - but one more attempt on my part - not so much to debate whether
to add text or not - but to come to a common understanding.
-----Original Message-----
From: Alvaro Retana (aretana)
Sent: Friday, April 07, 2017 2:45 PM
To: Les Ginsberg (ginsberg); Robert Sparks; gen-art(_at_)ietf(_dot_)org
Cc: draft-ietf-isis-auto-conf(_dot_)all(_at_)ietf(_dot_)org;
ietf(_at_)ietf(_dot_)org;
isis-wg(_at_)ietf(_dot_)org
Subject: Re: Genart last call review of draft-ietf-isis-auto-conf-04
On 4/7/17, 5:30 PM, "Les Ginsberg (ginsberg)"
<ginsberg(_at_)cisco(_dot_)com>
wrote:
Les:
Hi!
System-id duplication is a problem for any deployment - not just
autoconfig deployments. And it will be disruptive in any network
until it is
resolved.
The only thing autoconfig has added is a way to resolve this w/o
manual intervention. This in no way increases the vulnerability nor
the disruption the attacker can produce. (Yes - I state that quite
intentionally).
I don’t know about Robert, but that is part of the discussion I would
like to see.
Yes, duplicate system-ids have always been a potential problem, but
this document introduces a new de-duplication mechanism that results
not just in unsync’d databases, but in restarting adjacencies – so at
least the manifestation of the problem is different.
[Les:] The "problem" exists as long as the duplicate system-ids exist. The
recovery mechanism does not introduce new problems - it actually acts to
minimize the duration of the problem. One could argue (and I am NOT doing
so) that automated resolution could be a benefit in all deployments. I think
the issue in non-autoconfig deployments is that since systems have been
manually provisioned we cannot assume that network operators want us to
automatically change the config on one of their boxes. Though, who knows -
maybe we will get asked to use this extension outside of autoconfig
deployments.
It is necessary to have such a mechanism in autoconfig deployments since
there is - by default - no manual intervention. But to characterize this as
adding risk is incorrect IMO.
[Bing] I agree with Les that sys-id duplication attack is not an "adding" risk.
But maybe we could add a bit more text to explain why this document RECOMMNED
to implement Auth TLV.
Proposed added text in 3.5.1 (Authentication TLV) as below:
"The use of authentication is incompatible with auto-configuration as it
requires some manual configuration. However, there might be some users would
like to pay the effort of manual configuration to mitigate some security attack
(e.g. a malicious node crafts packet to intentionally cause the Sys-ID
duplication procedure continuously).
Thus, it is RECOMMENED that IS-IS... (the same as existing text).
Do you think it's OK?
Best regards,
Bing
Les
So you are asking us to repeat a discussion which has already been
held in the context of RFC 5304 and RFC 5310.
It would be more appropriate to add the normal reference to RFC
5304/5310 in the Security section than what you propose.
I don’t think it hurts to add a reference to those RFCs, but they are
both about adding authentication – the problem in this document is
exacerbated by the fact that there’s no authentication by default.
The lower layer authentication mechanisms are quite weak, specially
knowing that, if in a home environment, for example, it may be
relatively easy to connect to the WiFi network.
Alvaro.