Hi Qin,
Thank you for your response.
* RFC 3567 (for IS-IS) is obsoleted by RFC 5304. Unfortunately RFC 5304 still
uses HMAC-MD5, which would be considered insecure nowadays.
* RFC 2154 is very old and Experimental (and only supports RSA-MD5 signatures).
I'm not an OSPF expert by any means, but I'm willing to bet that there are no
production implementations of this RFC. (I'm willing to be proven wrong). Is
there another RFC that defines a protection mechanism for OSPF?
All in all, there appear to be no good options for the IGP.
To your last point, when I mentioned decoupling the mechanisms, I was
suggesting to use the extension you define even if the IGP *cannot* be secured.
If you think this is reasonable, please add such text to the Security
Considerations.
Thanks,
Yaron
On 8/9/21, 16:09, "Qin Wu" <[email protected]> wrote:
Thanks Yaron for valuable comments, please see my reply inline below.
-----邮件原件-----
>发件人: Yaron Sheffer via Datatracker [mailto:[email protected]]
>发送时间: 2021年8月6日 3:25
>收件人: [email protected]
>抄送: [email protected];
[email protected]; [email protected]
>主题: Secdir last call review of
draft-ietf-lsr-pce-discovery-security-support-05
>Reviewer: Yaron Sheffer
>Review result: Not Ready
>This document defines a mechanism (a TLV) to advertise the PCE Protocol
security required (use of TCP-AO and its key ID, or alternatively use of TLS)
within the routing protocol being used.
>* Sec. 3.1: I don't understand why "SHOULD advertise" and not MUST.
Especially given the strict client behavior defined later.
[Qin]: I believe "SHOULD advertise" is consistent with client behavior
defined later, i.e., we apply SHOULD NOT language to the client behavior.
I am not sure we should change it into strong language with MUST. Since if
IGP advertisement doesn't include TCP-AO
support flag bit or TLS support flag bit, NMS may fall back to configure
both PCC and PCE server to support TCP-AO or TLS. That's one of reason I think
why we choose to use SHOULD language.
>* Sec. 3.1: should we also say something about the case where both methods
are advertised, and whether we recommend for the client to use one of them over
the other?
[Qin]: It is up to local policy, which has bee clarified in the end of
section 3.1. Hope this clarify.
>* Sec. 4: typo (appears twice) - "to be carried in the PCED TLV of the for
use".
[Qin]:Thanks, have fixed them in the local copy.
>* Sec. 7: this phrase appears to be essential to security of this
mechanism: "it MUST be insured that the IGP is protected for authentication and
integrity of the PCED TLV". I would expect more guidance: how can this property
be ensured in the relevant IGPs?
[Qin]:I think mechanism defined in [RFC3567] and [RFC2154] can be used to
ensure authenticity and integrity of OSPF LSAs or ISIS LSPs and their TLVs.
Here is the proposed changes:
OLD TEXT:
"
Thus before advertisement of
the PCE security parameters, it MUST be insured that the IGP is
protected for authentication and integrity of the PCED TLV if the
mechanism described in this document is used.
"
NEW TEXT:
"
Thus before advertisement of
the PCE security parameters, it MUST be insured that the IGP is
protected for authentication and integrity of the PCED TLV with
mechanisms defined in [RFC3567][RFC2154] if the
mechanism described in this document is used.
"
>* Also, a possibly unintended consequence of this requirement is that if
the IGP cannot be protected in a particular deployment/product, this mechanism
would not be used. Please consider if this is likely to happen and whether we
want to forego PCEP transport >security in such cases. My gut feel (not based
on experience in such networks) is that the threat models are different enough
that we should decouple the security of IGP from that of PCEP.
[Qin] I agree IGP security should be separated from PCEP security. IGP
extension defined in this document is used by the PCC to select PCE server with
appropriate security mechanism. On the other hand, Operator can either use IGP
advertisement for PCEP security capability or rely on local policy to select
PCE. If operator feels IGP advertisement is not secure, he can fall back to
local policy or rely on manual configuration. Hope this clarifies.
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