Re: [secdir] Secdir review of draft-ietf-mpls-ldp-gtsm-07

"Rajiv Asati (rajiva)" <rajiva@cisco.com> Fri, 01 June 2012 21:28 UTC

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Date: Fri, 1 Jun 2012 16:28:28 -0500
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From: "Rajiv Asati (rajiva)" <rajiva@cisco.com>
To: "Brian Weis (bew)" <bew@cisco.com>
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Cc: draft-ietf-mpls-ldp-gtsm.all@tools.ietf.org, The IESG <iesg@ietf.org>, secdir@ietf.org
Subject: Re: [secdir] Secdir review of draft-ietf-mpls-ldp-gtsm-07
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Hi Brian,

Thanks. Will work with my co-author to get the next version submitted.

Cheers,
Rajiv


> -----Original Message-----
> From: Brian Weis (bew)
> Sent: Friday, June 01, 2012 5:11 PM
> To: Rajiv Asati (rajiva)
> Cc: secdir@ietf.org; The IESG;
draft-ietf-mpls-ldp-gtsm.all@tools.ietf.org
> Subject: Re: Secdir review of draft-ietf-mpls-ldp-gtsm-07
> 
> Hi Rajiv,
> 
> Your proposed text looks good to me. I think it's good to go with this
added.
> 
> Thanks,
> Brian
> 
> 
> On Jun 1, 2012, at 1:37 PM, Rajiv Asati (rajiva) wrote:
> 
> > Hi Brian,
> >
> > Really appreciate your critical review and suggestions.
> >
> > I agree to your both of your suggestions, and would propose the
> > following text for us to include in the next revision.
> >
> >
> > //
> > As discussed in section 3, it is possible that
> > - GTSM for LDP may not always be enforced on a single-hop LDP
peering
> > session and may still be susceptible to forged/spoofed protocol
> > packets, if the single-hop LDP peering session is set up using
> > Extended Discovery.
> > - GTSM for LDP may cause LDP peering session to not get established
> > (or torn down), if IP routing ever declares that the directly
> > connected peer is more than one hop away.
> > Suffice to say, use of cryptographic integrity (e.g., RFC 5925) is
> > recommended as an alternate solution for detecting forged protocol
> > packets (especially for the multi-hop case).
> > //
> >
> > Cheers,
> > Rajiv
> >
> >
> >> -----Original Message-----
> >> From: Brian Weis (bew)
> >> Sent: Friday, June 01, 2012 2:16 PM
> >> To: secdir@ietf.org; The IESG
> >> Cc: draft-ietf-mpls-ldp-gtsm.all@tools.ietf.org
> >> Subject: Secdir review of draft-ietf-mpls-ldp-gtsm-07
> >>
> >> I have reviewed this document as part of the security directorate's
> > ongoing
> >> effort to review all IETF documents being processed by the IESG.
> >> These comments were written primarily for the benefit of the
security
> >> area directors. Document editors and WG chairs should treat these
> >> comments just like any other last call comments.
> >>
> >> This document applies the Generalized TTL Security Mechanism (GTSM)
> >> mechanism defined in RFC 5082. This mechanism is used by routing
> >> protocols as a low-cost non-cryptographic method intended to
> >> frustrate
> > off-
> >> path attackers.  It is applicable when the peer is known to be
> > connected by a
> >> single hop.
> >>
> >> The security considerations of this draft mostly point to RFC
5082's
> >> extensive security considerations section, which is appropriate.
> > However
> >> because this I-D discusses multi-hop cases in greater detail it
would
> > be
> >> appropriate for the security considerations section to also discuss
> > multi-hop
> >> a bit more. Here are some thoughts for that:
> >>
> >> 1) Use of cryptographic integrity (e.g., RFC 5925) should be
> > recommended as
> >> an alternate solution for detecting forged protocol packets in the
> > multi-hop
> >> case.
> >>
> >> 2) GTSM is expected to be enabled by default for Basic Discovery
> > because
> >> it's usually a single-hop, and disabled for Extended Discovery
> >> because
> > it's
> >> usually multi-hop. But then Section 3 mentions several exceptions,
> > which
> >> apparently need to be administratively configured away from the
> > defaults.
> >> Failing to do this when needed results in security risks in either
> > case: either
> >> GTSM isn't deployed when it should be and the router is
inadvertently
> > open
> >> to spoofing, or GTSM is deployed when it shouldn't be and this
> >> results
> > in an
> >> availability issue because LDP packets will be dropped before
> >> reaching
> > the
> >> LDP peer. This should be stated in the Security Considerations.
> >>
> >> Brian
> >>
> >>
> >>
> >>
> >>
> >
> 
> 
> --
> Brian Weis
> Security Standards and Technology, SRTG, Cisco Systems
> Telephone: +1 408 526 4796
> Email: bew@cisco.com
> 
> 
> 
>