[Ntp] Antw: [EXT] Re: Last Call: <draft-ietf-ntp-yang-data-model-10.txt> (A YANG Data Model for NTP) to Proposed Standardsecurity
Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de> Tue, 09 February 2021 11:44 UTC
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Date: Tue, 09 Feb 2021 12:44:40 +0100
From: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
To: daedulus@btconnect.com, Hal Murray <hmurray@megapathdsl.net>
Cc: Dieter Sibold <dsibold.ietf@gmail.com>, ek.ietf@gmail.com, draft-ietf-ntp-yang-data-model@ietf.org, last-call@ietf.org, "ntp@ietf.org" <ntp@ietf.org>, "ntp-chairs@ietf.org" <ntp-chairs@ietf.org>
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Subject: [Ntp] Antw: [EXT] Re: Last Call: <draft-ietf-ntp-yang-data-model-10.txt> (A YANG Data Model for NTP) to Proposed Standardsecurity
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>>> Hal Murray <hmurray@megapathdsl.net> schrieb am 09.02.2021 um 10:34 in Nachricht <20210209093446.E11F8406061@ip-64-139-1-69.sjc.megapath.net>: > daedulus@btconnect.com said: >> RFC8573 seems clear that MD5 must not be used to effect security for NTP > but >> this I‑D imports iana‑crypt‑hash which allows MD5 without any restriction, >> so is MD5 allowed or not? > > "Allowed" is the key word. Just because somebody published an RFC doesn't > mean that all the gear out in the field will get updated. As Harlan pointed > > out, there is a very very long tail on NTP deployments. > > I think it makes sense for iana‑crypt‑hash to include slots for historic > items. If nothing else, it is a good place to say "historic" or > "deprecated" > and give references to the details. > > If you think a Yang model should discourage using MD5, then I suggest adding > > words to say that. Better would be to phrase things so that it also > includes > other algorithms that get kicked out of the club after the RFC is published. > > I don't know of any place that publishes an up‑to‑date list of crypto‑hashing > algorithms and their status. > > ‑‑‑‑‑‑‑‑‑‑ > > I'm looking at iana‑crypt‑hash@2014‑08‑06.yang > > It says: > id | hash function | feature > ‑‑‑+‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑+‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑‑ > 1 | MD5 | crypt‑hash‑md5 > 5 | SHA‑256 | crypt‑hash‑sha‑256 > 6 | SHA‑512 | crypt‑hash‑sha‑512 AFAIK DES does no longer work with NTPv4, but it probably would in NTPv3. So would leaving out DES actually break NTPv3 compatibility? (Not that I suggest to use DES, but who knows what old NTPv3 gear actually does). It seems as per RFC 1305 DES is the only algorithm supported ("Cryptographic Keys (sys.key): This is a set of 64-bit DES keys." on page 64) > > If NTP is the only use, then I'd suggest adding a deprecated note. But I > assume that is used by other than NTP so that may not be appropriate. But > maybe if MD5 is deprecated for NTP it should be deprecated for other uses > too. > ??? > > What happened to slots 2, 3, and 4? > > Existing NTP code also supports SHA‑1 > > RFC 8573 that deprecated using MD5 with NTP suggests using AES‑CMAC. Note > that is CMAC rather than HMAC and that NTP uses it's own scheme rather than > HMAC as described in RFC 6151. > > The NTPsec code supports any hash (or CMAC) algorithm that the underlying > library from OpenSSL supports. > > ‑‑ > These are my opinions. I hate spam. > > > > _______________________________________________ > ntp mailing list > ntp@ietf.org > https://www.ietf.org/mailman/listinfo/ntp
- [Ntp] Antw: [EXT] Re: Last Call: <draft-ietf-ntp-… Ulrich Windl