From isms-bounces@lists.ietf.org Fri Dec 08 17:25:16 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gso9Y-0005Kg-1v; Fri, 08 Dec 2006 17:25:12 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gso9W-0005KM-PH for isms@ietf.org; Fri, 08 Dec 2006 17:25:10 -0500 Received: from kyoto.netlab.nec.de ([195.37.70.21]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gso9U-00013u-Ar for isms@ietf.org; Fri, 08 Dec 2006 17:25:10 -0500 Received: from [192.168.1.128] (unknown [91.89.53.224]) by kyoto.netlab.nec.de (Postfix) with ESMTP id 4DE5413CF82 for ; Fri, 8 Dec 2006 23:29:39 +0100 (CET) Date: Fri, 08 Dec 2006 22:33:36 +0100 From: Juergen Quittek To: isms@ietf.org Message-ID: <197AB6F199EEE7F03D82E5D0@753F3B888A9969457862729D> X-Mailer: Mulberry/4.0.5 (Mac OS X) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Spam-Score: 0.0 (/) X-Scan-Signature: cf4fa59384e76e63313391b70cd0dd25 Cc: Subject: [Isms] draft minutes of the ISMS session in San Diego X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Dear all, Please find draft minutes of our session in San Diego at Please check them and send your comments or requests for changes before December 22nd. Thanks, Juergen -- Juergen Quittek quittek@netlab.nec.de Tel: +49 6221 4342-115 NEC Europe Ltd., Network Laboratories Fax: +49 6221 4342-155 Kurfuersten-Anlage 36, 69115 Heidelberg, Germany http://www.netlab.nec.de _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Tue Dec 12 06:58:36 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gu6HE-0001r6-21; Tue, 12 Dec 2006 06:58:28 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gu6HC-0001qw-4o for isms@ietf.org; Tue, 12 Dec 2006 06:58:26 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gu6H9-0006iS-4c for isms@ietf.org; Tue, 12 Dec 2006 06:58:26 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id 3CDD25AD06; Tue, 12 Dec 2006 12:58:20 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 13358-09; Tue, 12 Dec 2006 12:58:16 +0100 (CET) Received: from boskop.local (unknown [10.50.250.214]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id 64D7A5971D; Tue, 12 Dec 2006 12:58:16 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id B03458F7B38; Tue, 12 Dec 2006 12:57:15 +0100 (CET) Date: Tue, 12 Dec 2006 12:57:15 +0100 From: Juergen Schoenwaelder To: Juergen Quittek Subject: Re: [Isms] draft minutes of the ISMS session in San Diego Message-ID: <20061212115715.GA116@boskop.local> Mail-Followup-To: Juergen Quittek , isms@ietf.org References: <197AB6F199EEE7F03D82E5D0@753F3B888A9969457862729D> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="mYCpIKhGyMATD0i+" Content-Disposition: inline In-Reply-To: <197AB6F199EEE7F03D82E5D0@753F3B888A9969457862729D> User-Agent: Mutt/1.5.12-2006-07-14 X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: 850245b51c39701e2700a112f3032caa Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: j.schoenwaelder@iu-bremen.de List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org --mYCpIKhGyMATD0i+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Dec 08, 2006 at 10:33:36PM +0100, Juergen Quittek wrote: > Please find draft minutes of our session in San Diego at > > > Please check them and send your comments or requests for > changes before December 22nd. Juergen, attached is a new version with several typos fixed. /js -- Juergen Schoenwaelder {International|Jacobs} University Bremen P.O. Box 750 561, 28725 Bremen, Germany --mYCpIKhGyMATD0i+ Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="isms.txt" ======================================================= Integrated Security Model for SNMP WG (isms) at IETF 67 San Diego, Thursday, November 9, 2006 at 1510-1610 Taken by Juergen Quittek ======================================================= Chairs: Juergen Schoenwaelder Juergen Quittek Agenda: 0) Session summary 1) Agenda bashing, WG status 2) Discussion of existing WG drafts 3) Review of ISMS milestones 4) Performance analysis of SNMP over SSH ---------------- 0) Session summary As agreed at the last meeting, one of the two existing WG documents was split into two. The resulting three documents describe a transport subsystem for SNMP, a transport security model for SNMP, and a SSH security model for SNMP. The new document structure is more modular and simplifies the potential future specification of other security models, for example, a TLS security model in addition to the SSH model that the ISMS WG develops. The new document structure was approved by the WG and by the responsible AD Sam Hartman. For the transport subsystem for SNMP and the transport security model for SNMP all open issues have been resolved and the next versions of these documents will enter WGLC. The SSH security model for SNMP will probably need two more revisions to be ready for WGLC. The biggest open issue is the authentication for notifications. The charter contains two more documents that do not yet exist. One describes the usage of RADIUS for the SSH security model. We have an individual draft, but kept it on hold until the SSH security model had become sufficiently stable. This has been achieved with the current version of the SSH security model. Now, work on the RADIUS document can go on and the initial WG draft is planned for December. The last document on the charter is an applicability statement for ISMS. With the new modular structure, the WG considers it preferable to have rather applicability statements per module instead of a generic one for ISMS. It was agreed to drop this document and instead add a specific applicability statement to the SSH security module. This change was approved by the responsible AD. ---------------- 1) WG Status (Juergen Quittek) Only two of the four planned WG documents do exist yet. One of them has been split. All are behind schedule. Therefore, we need a discussion of milestones later today. ---------------- 2) Discussion of existing WG drafts (David Harrington) - Transport Subsystem for SNMP draft-ietf-isms-tmsm-04.txt - Transport Security Model for SNMP draft-ietf-isms-transport-security-model-00.txt - Secure Shell Transport Model for SNMP draft-ietf-isms-secshell-05.txt The main change since last meeting is the new structure containing: - a transport subsystem - an SSH transport module - a session security model This structure was agreed at the last meeting, now it has been reflected by the document structure. David H presented current ISMS issues. For the transport subsystem there are - #1a How to integrated the transport subsystem into the current SNMP architecture? shall we pass all parameters through all involved SNMP ASIs? - #1b Which transport addressing scheme to be used (RFC3417, RFC3419, RFC4001)? RFC3417 (snmpDomains) are the preferred choice. Solves also issue #1a Jeff Hutzelman: What is in that SNMP address type? David H: The hostname. Jeff H: This does not have an effect our work so far? David H: Right. Jeff H: Sounds very SNMP-specific, but works OK. This is a solution we can solve within our WG scope. Other solutions might require extensions to SNMP architecture and would be out of scope. - #2 The transport subsystem MIB is not needed. Will be eliminated. All transport subsystem issues are solved. For the SSH transport model there are the following issues: - #1 It is not independent of the security model. May be possible to solve, but needs more work. Q: Why does it need to be independent? David H: You might want to use two different security models. Bert: Is the community name the securityName? David H: This may be wrong. We will fix it. Wes Hardaker: The implementers will do what needs to be done with the bits. What is separated here in the architecture may probably no be separated in an implementation. David H: Agreed. Jeff H: Can you still use USM for transport? David H: Implementors still have alternatives when implementing systems. They may not implement a transport model, but we want to make a recommendation on how it can be done. We still have to work through all the elements of procedure. Juergen S: (via Jabber) I think the security model is determined by the SNMPv3 message. We just have to check that the transport security model properly checks that a valid tmStateReference is available from a secure transport. Wes: The implementers will do what need to be done. Separation is hard to get. They are bound. Sam Hartman: Is the proposal to separate the TMSM from SSH TM so you can use another security model with SSH? David H: Yes. Juergen S: The transport security model which is left essentially looks at the tmStateReference to pick up the required data from a secure transport and then passes things on. Since the security model is determined by the SNMPv3 message, we can in principle run other security models on top of SSH. Wes: You are adding a lot of complexity with very little gain. Your user base will be pretty small. Jeff H: It is not necessarily additional complexity, but an abstraction that the security model and the transport model are separate. David H: The next version of the document will have this problem solved or state that it cannot be solved. - #2 The SSH TM does not do everything that USM can do. USM has a built-in discovery mechanism. We do not yet have a discovery mechanism built into the SSH TM or the Transport SM. One solution would be saying 'Let USM do this discovery of the context engine ID'. Wes: USM does not discover the context engine ID, but the security engine ID. David H: Correct. It's the security engine ID. At this point in time we use USM for that discovery. I would like at some time in the future to see a new mechanism doing discovery for any kind of transport model and any security model. Jeff H: SSH does not need a security engine ID? David H: No. We discover the security engine ID only in order to get the context engine ID. We also rely on USM if you want to send a notification and no session has been set up yet. Eliot Lear: (via Jabber) If you are using USM for notifications, you have to define the USM user on every agent. What we are doing here is getting around that. In effect you are saying you cannot use notification if you want to benefit from ISMS. David H: Call home is not on our charter. If I want a device to send some traps, I want to configure anyway where to send them to. I don't want them to be sent to random destinations. - #3 We had a teleconference on asymmetric notification authentication but did not find a solution. There are three options described on the slides. For the transport security model issues are solved. Some details need to be worked out in the next revision, but then we should be close to WG last call. ---------------- 3) Review of ISMS milestones (Juergen Quittek) ISMS is behind schedule. Planned was to submit the transport subsystem document and the SSH security model to the IESG in August 06. Now we have split the planned SSH security model into a transport security model and a SSH transport model. Juergen Q: Does anybody have a problem with splitting this document? Nobody spoke up. David H: The transport subsystem will be ready for WGLC after the next revision. The security model may also be ready after the next revision. The SSH transport model needs some more work. Juergen Q: Let's set the deadlines to February for the first two and to April for the SSH transport model. The document on RADIUS usage for the SSH security model does not exist as a WG draft but as an individual I-D. This was OK, since the SSH security model has been a moving target. But now it seems to have become sufficiently stable to start working on the RADIUS document. Juergen Q: Can we have a first version of the WG I-D in December. David Nelson: We can have a document reflecting the current structure by December. The charter contains another document: the ISMS applicability statement. It was suggested to not have this document, but move applicability statements into the SSH transport model. David H: The applicability of the SSH transport model do not necessarily impact other transport models. Having its applicability stated in the same document is probably the best way to go. Juergen Q: This means we have to extend the SSH transport I-D by an applicability section. Juergen Q: Does anyone have a problem with removing this document from our charter? Nobody spoke up. ---------------- 4) Performance analysis of SNMP over SSH (Vladislav Marinov) Vladislav presented measurements of performance for session-based security vs. message-based security with a prototype implementation. Wes: Excellent results. There are some caveats. The NET-SNMP implementation of SNMPv3 was not implemented for speed and uses some obviously slow mechanisms that can be improved. We use OIDs as index and we don't do caching everytime a packet comes in we do a complex lookup. --mYCpIKhGyMATD0i+ Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms --mYCpIKhGyMATD0i+-- From isms-bounces@lists.ietf.org Wed Dec 13 10:41:49 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWEv-0002yE-0x; Wed, 13 Dec 2006 10:41:49 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWEu-0002y9-6K for isms@ietf.org; Wed, 13 Dec 2006 10:41:48 -0500 Received: from alnrmhc11.comcast.net ([204.127.225.91]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GuWEr-0008Kl-I4 for isms@ietf.org; Wed, 13 Dec 2006 10:41:48 -0500 Received: from harrington73653 (c-24-128-104-207.hsd1.nh.comcast.net[24.128.104.207]) by comcast.net (alnrmhc11) with SMTP id <20061213154138b1100k4t5be>; Wed, 13 Dec 2006 15:41:38 +0000 From: "David Harrington" To: Date: Wed, 13 Dec 2006 10:38:32 -0500 Message-ID: <137701c71ecc$bf3769f0$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: AccezLIoEK+9Ik9BSTWfBgM1aFTtpg== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Spam-Score: 0.0 (/) X-Scan-Signature: e5ba305d0e64821bf3d8bc5d3bb07228 Cc: Subject: [Isms] unknownTransportModels X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, Time to starrt some discussions here. Is anybody out there???? I am closing in on th enext revision of the transport subsystem document, and there are a few questions which have been raised that I am considering how to address. RFC3412 (the messaging subsystem) has an unknownSecurityModels that counts the number of packets **received** that were dropped because the security model (presumably extracted from the incoming message) was unknown. This counter is never incremented for outgoing messages. An unknownTransportModels counter would probably never get incremented. For outgoing messages, this is an implementation debugging issue that does not need to be exposed in a mib module. For incoming messages, we would never get the message if a transport model doesn't exist to support the underlying transport, and we certainly would'nt get it if the underlying transport doesn't exist. So I don't think an unknownTransportModels makes protocol sense. Am I overlooking any scenarios where this counter would be useful? David Harrington dharrington@huawei.com dbharrington@comcast.net ietfdbh@comcast.net _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 13 11:00:33 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWWz-0004ox-E3; Wed, 13 Dec 2006 11:00:29 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWWy-0004oK-DP for isms@ietf.org; Wed, 13 Dec 2006 11:00:28 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GuWWt-0002PR-IB for isms@ietf.org; Wed, 13 Dec 2006 11:00:28 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id AB80E59095; Wed, 13 Dec 2006 17:00:08 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 19594-02; Wed, 13 Dec 2006 17:00:05 +0100 (CET) Received: from boskop.local (unknown [10.50.250.214]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id A75DC59090; Wed, 13 Dec 2006 17:00:02 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id B35EA8F9E4C; Wed, 13 Dec 2006 17:00:00 +0100 (CET) Date: Wed, 13 Dec 2006 17:00:00 +0100 From: Juergen Schoenwaelder To: David Harrington Subject: Re: [Isms] unknownTransportModels Message-ID: <20061213160000.GC3980@boskop.local> Mail-Followup-To: David Harrington , isms@ietf.org References: <137701c71ecc$bf3769f0$0600a8c0@china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <137701c71ecc$bf3769f0$0600a8c0@china.huawei.com> User-Agent: Mutt/1.5.10i X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: 856eb5f76e7a34990d1d457d8e8e5b7f Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: j.schoenwaelder@iu-bremen.de List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org On Wed, Dec 13, 2006 at 10:38:32AM -0500, David Harrington wrote: > An unknownTransportModels counter would probably never get > incremented. For outgoing messages, this is an implementation > debugging issue that does not need to be exposed in a mib module. For > incoming messages, we would never get the message if a transport model > doesn't exist to support the underlying transport, and we certainly > would'nt get it if the underlying transport doesn't exist. > > So I don't think an unknownTransportModels makes protocol sense. I can't think of a use case for such a counter. /js -- Juergen Schoenwaelder {International|Jacobs} University Bremen P.O. Box 750 561, 28725 Bremen, Germany _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 13 11:22:46 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWsL-00087m-1B; Wed, 13 Dec 2006 11:22:33 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuWsJ-00087b-GP for isms@ietf.org; Wed, 13 Dec 2006 11:22:31 -0500 Received: from alnrmhc14.comcast.net ([204.127.225.94]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GuWsH-0005CE-6P for isms@ietf.org; Wed, 13 Dec 2006 11:22:31 -0500 Received: from harrington73653 (c-24-128-104-207.hsd1.nh.comcast.net[24.128.104.207]) by comcast.net (alnrmhc14) with SMTP id <20061213162227b1400mina7e>; Wed, 13 Dec 2006 16:22:27 +0000 From: "David Harrington" To: Date: Wed, 13 Dec 2006 11:19:18 -0500 Message-ID: <137801c71ed2$7317bf10$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: Acce0kAVLiZxKpyUQ7SpdMRgwQkjSA== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Spam-Score: 0.0 (/) X-Scan-Signature: b4a0a5f5992e2a4954405484e7717d8c Cc: Subject: [Isms] snmpTransportModel X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, At ietf67, we agreed to use TDomain and TAddress (RFC3417) rather than other addressing approaches. So the new revision will have a TDomain of snmpSSHDomain and a TAddress of snmpSSHAddress. The SNMP-TRANSPORT-MIB (Transport-Subsystem-MIB in -04-) has no useful objects so far, and at ietf67, we agreed to eliminate the MIB module. The MIB module contains the Textual Convention SnmpTransportModel, which parallels the SnmpSecurityModel and SnmpMessageProcessingModel T-Cs from RFC3411. However, we never pass SnmpTransportModel anyplace, or refer to it in any MIB module, so far. So the only purpose, at this point, would be to use SnmpTransportModel to define an IANA registry for IETF transport models, and to standardize how enterprises can identify their own transport models, but if it is never actually used, this may not be useful. So we need to decide whether to keep the textual convention, on the assumption it might be useful someday (not a very good justification for a feature), or scrap it (and possibly need to define it in a specific transport model, which makes document housekeeping and functional modularity more complex). There is one place where having an SnmpTransportModel might be useful. A "session" is currently identified by transport[Domain,Address] and security[Model,Name,Level]. If somebody wanted to define another SSH-based transport model, which used the same addressing domain/address, then this really should be expanded to be transport[Model,Domain,Address] and security[Model,Name,Level]. There is not necessarily a 1:1 mapping between transport models and transport domain/addressing. This would mean we would need to modify the ASIs (or make sure this ends up in the cache and LCD, which is about the same thing) to pass the transport model identifier. Currently, transportDomain implies transportModel, and the dispatcher uses transportDomain to determine how to dispatch outgoing messages to the approrpiate transport model. This usage implicitly assumes a 1:1 mapping between transport model and transport domain/addressing. We could make that explicit. If another transport model wants to use the same address format, they could define a new domain and then they can utilize the same address format. For example, if another SSH transport model were created (say to use as the "SSH-VPN" approach), they would need to define a new domain (snmpSSHVPNDomain), but could use the same snmpSSHAddress specification used by snmpSSHDomain. If this is viable, then we do not need the registration mechanisms for snmp transport models from SNMP-TRANSPORT-MIB. I will note that IANA does not maintain a registry for TDomains, so it may be somewhat harder to prevent assignment collisions, or to find definitons for enterprise-assigned domains (registered in enterprise-specific subtrees). We could ask IANA to create a registry of TDomains. I can envision seeing more development of Tdomains than security models or messaging models, so a registry might be useful. David Harrington dharrington@huawei.com dbharrington@comcast.net ietfdbh@comcast.net _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 13 14:49:08 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gua63-0004Ci-12; Wed, 13 Dec 2006 14:48:55 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gua62-0004Cd-5r for isms@ietf.org; Wed, 13 Dec 2006 14:48:54 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gua60-0002iQ-GS for isms@ietf.org; Wed, 13 Dec 2006 14:48:54 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id 66F9C5AD32; Wed, 13 Dec 2006 20:48:51 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 06824-05; Wed, 13 Dec 2006 20:48:48 +0100 (CET) Received: from boskop.local (unknown [10.50.250.214]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id 14CE05AB9C; Wed, 13 Dec 2006 20:48:48 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id 396E28FA182; Wed, 13 Dec 2006 20:48:46 +0100 (CET) Date: Wed, 13 Dec 2006 20:48:45 +0100 From: Juergen Schoenwaelder To: David Harrington Subject: Re: [Isms] snmpTransportModel Message-ID: <20061213194845.GA4358@boskop.local> Mail-Followup-To: David Harrington , isms@ietf.org References: <137801c71ed2$7317bf10$0600a8c0@china.huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <137801c71ed2$7317bf10$0600a8c0@china.huawei.com> User-Agent: Mutt/1.5.10i X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: cd26b070c2577ac175cd3a6d878c6248 Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: j.schoenwaelder@iu-bremen.de List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org On Wed, Dec 13, 2006 at 11:19:18AM -0500, David Harrington wrote: > At ietf67, we agreed to use TDomain and TAddress (RFC3417) rather than > other addressing approaches. So the new revision will have a TDomain > of snmpSSHDomain and a TAddress of snmpSSHAddress. > > The SNMP-TRANSPORT-MIB (Transport-Subsystem-MIB in -04-) has no useful > objects so far, and at ietf67, we agreed to eliminate the MIB module. > > The MIB module contains the Textual Convention SnmpTransportModel, > which parallels the SnmpSecurityModel and SnmpMessageProcessingModel > T-Cs from RFC3411. However, we never pass SnmpTransportModel anyplace, > or refer to it in any MIB module, so far. > > So the only purpose, at this point, would be to use SnmpTransportModel > to define an IANA registry for IETF transport models, and to > standardize how enterprises can identify their own transport models, > but if it is never actually used, this may not be useful. > > So we need to decide whether to keep the textual convention, on the > assumption it might be useful someday (not a very good justification > for a feature), or scrap it (and possibly need to define it in a > specific transport model, which makes document housekeeping and > functional modularity more complex). > > There is one place where having an SnmpTransportModel might be useful. > A "session" is currently identified by transport[Domain,Address] and > security[Model,Name,Level]. If somebody wanted to define another > SSH-based transport model, which used the same addressing > domain/address, then this really should be expanded to be > transport[Model,Domain,Address] and security[Model,Name,Level]. There > is not necessarily a 1:1 mapping between transport models and > transport domain/addressing. > > This would mean we would need to modify the ASIs (or make sure this > ends up in the cache and LCD, which is about the same thing) to pass > the transport model identifier. Lets not over-engineer this. I think the transportDomain is a perfect way to tell which transport model to use. > Currently, transportDomain implies transportModel, and the dispatcher > uses transportDomain to determine how to dispatch outgoing messages to > the approrpiate transport model. This usage implicitly assumes a 1:1 > mapping between transport model and transport domain/addressing. We > could make that explicit. Yes. > If another transport model wants to use the same address format, they > could define a new domain and then they can utilize the same address > format. For example, if another SSH transport model were created (say > to use as the "SSH-VPN" approach), they would need to define a new > domain (snmpSSHVPNDomain), but could use the same snmpSSHAddress > specification used by snmpSSHDomain. If this is viable, then we do not > need the registration mechanisms for snmp transport models from > SNMP-TRANSPORT-MIB. Yes, I believe this is viable. > I will note that IANA does not maintain a registry for TDomains, so it > may be somewhat harder to prevent assignment collisions, or to find > definitons for enterprise-assigned domains (registered in > enterprise-specific subtrees). We could ask IANA to create a registry > of TDomains. I can envision seeing more development of Tdomains than > security models or messaging models, so a registry might be useful. RFC 4789 established a registry for OIDs below snmpDomains which are used to identify SNMP transport domains. A specification is required for new assignments. Since TDomain is an OID, there is no likelihood of collisions. Enterprise assignments may be hard to find but then they are probably not made with the intention to be interoperable in the first place. /js -- Juergen Schoenwaelder {International|Jacobs} University Bremen P.O. Box 750 561, 28725 Bremen, Germany _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 13 16:28:42 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GubeP-00011B-QO; Wed, 13 Dec 2006 16:28:29 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GubeN-0000z3-9k; Wed, 13 Dec 2006 16:28:27 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GubaD-0000qU-TG; Wed, 13 Dec 2006 16:24:15 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id C949C5AD4D; Wed, 13 Dec 2006 22:24:04 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 14174-06; Wed, 13 Dec 2006 22:24:01 +0100 (CET) Received: from boskop.local (unknown [10.50.250.214]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id 940C05AB9C; Wed, 13 Dec 2006 22:24:01 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id AFE928FA467; Wed, 13 Dec 2006 22:23:59 +0100 (CET) Date: Wed, 13 Dec 2006 22:23:59 +0100 From: Juergen Schoenwaelder To: isms@ietf.org, ngo@ietf.org Message-ID: <20061213212359.GA4888@boskop.local> Mail-Followup-To: isms@ietf.org, ngo@ietf.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.10i X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: 082a9cbf4d599f360ac7f815372a6a15 Cc: Subject: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: isms@ietf.org List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, I started an ID concerning engineID discovery. There was some discussion about this topic in the ISMS working group in the past and recently there was a thread on the "netconf goes on" (ngo) mailing list . ISMS is not really chartered to work on general engineID discovery. However, any real-world ISMS implementation needs to figure out a way how to do engineID discovery. The approach documented in the ID does provide a general discovery mechanism which has the benefit that it does not need any modifications to existing SNMPv3 standards (as far as I understand things). I am looking for review, feedback, criticism and suggestions. If we manage to find agreement on an approach, I am sure we can talk to the various ADs how we can best move this forward. Lets get a solution worked out first. Since the ISMS list is not really busy and since ISMS implementations kind of need engineID discovery to be acceptable in practice, I think it is fine to host further discussions here on this list (and I expect that a sufficient number of SNMP experts are following the ISMS list anyway). /js ----- Forwarded message from Internet-Drafts@ietf.org ----- To: i-d-announce@ietf.org Cc: From: Internet-Drafts@ietf.org Date: Wed, 13 Dec 2006 15:50:06 -0500 Subject: I-D ACTION:draft-schoenw-snmp-discover-00.txt Precedence: list Reply-To: internet-drafts@ietf.org Errors-To: i-d-announce-bounces@ietf.org A New Internet-Draft is available from the on-line Internet-Drafts directories. Title : Simple Network Management Protocol (SNMP) EngineID Discovery Author(s) : J. Schoenwaelder Filename : draft-schoenw-snmp-discover-00.txt Pages : 8 Date : 2006-12-13 To retrieve management information using the third version of the Simple Network Management Protocol (SNMP), it is necessary to know the identifier of the remote SNMP protocol engine. This document introduces a discovery mechanism which can be used to learn the engine identifier of a remote SNMP protocol engine. The proposed mechanism is independent of the features provided by SNMP security models and may be used also by other protocol interfaces to discover the engine identifier. A URL for this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-schoenw-snmp-discover-00.txt [...] _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 13 18:52:13 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GudtR-0001uq-Fn; Wed, 13 Dec 2006 18:52:09 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GudtQ-0001sf-1L; Wed, 13 Dec 2006 18:52:08 -0500 Received: from alnrmhc12.comcast.net ([206.18.177.52]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GudtM-0007x6-O1; Wed, 13 Dec 2006 18:52:08 -0500 Received: from harrington73653 (c-24-128-104-207.hsd1.nh.comcast.net[24.128.104.207]) by comcast.net (alnrmhc12) with SMTP id <20061213235201b1200bp64be>; Wed, 13 Dec 2006 23:52:01 +0000 From: "David Harrington" To: Date: Wed, 13 Dec 2006 18:48:45 -0500 Message-ID: <141301c71f11$41104980$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_NextPart_000_1414_01C71EE7.583A4180" X-Mailer: Microsoft Office Outlook 11 Thread-Index: AccfEToPOQzdi1JrRNqba98oEfFiNw== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Spam-Score: 0.0 (/) X-Scan-Signature: 68623d13ded64d34b180b4eed436a7d1 Cc: isms@ietf.org Subject: [Isms] Please publish X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org This is a multi-part message in MIME format. ------=_NextPart_000_1414_01C71EE7.583A4180 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Please publish this file as draft-ietf-isms-tmsm-05.txt Thanks, David Harrington dharrington@huawei.com dbharrington@comcast.net ietfdbh@comcast.net ------=_NextPart_000_1414_01C71EE7.583A4180 Content-Type: text/plain; name="draft-ietf-isms-tmsm-05.txt" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="draft-ietf-isms-tmsm-05.txt" Network Working Group D. Harrington Internet-Draft Huawei Technologies (USA) Intended status: Standards Track J. Schoenwaelder Expires: June 16, 2007 International University Bremen December 13, 2006 Transport Subsystem for the Simple Network Management Protocol (SNMP) draft-ietf-isms-tmsm-05 Status of This Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on June 16, 2007. Copyright Notice Copyright (C) The IETF Trust (2006). Abstract This document describes a Transport Subsystem, extending the Simple Network Management Protocol (SNMP) architecture defined in RFC 3411. This document describes a subsystem to contain transport models, comparable to other subsystems in the RFC3411 architecture. As work is being done to expand the transport to include secure transport such as SSH and TLS, using a subsystem will enable consistent design and modularity of such transport models. This document identifies Harrington & Schoenwaelder Expires June 16, 2007 [Page 1] =0C Internet-Draft SNMP Transport Subsystem December 2006 and discusses some key aspects that need to be considered for any transport model for SNMP. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. The Internet-Standard Management Framework . . . . . . . . 3 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 3 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Requirements of a Transport Model . . . . . . . . . . . . . . 6 3.1. Message Security Requirements . . . . . . . . . . . . . . 6 3.1.1. Security Protocol Requirements . . . . . . . . . . . . 6 3.2. SNMP Requirements . . . . . . . . . . . . . . . . . . . . 7 3.2.1. Architectural Modularity Requirements . . . . . . . . 7 3.2.2. Access Control Requirements . . . . . . . . . . . . . 11 3.2.3. Security Parameter Passing Requirements . . . . . . . 12 3.3. Session Requirements . . . . . . . . . . . . . . . . . . . 14 3.3.1. Session Establishment Requirements . . . . . . . . . . 14 3.3.2. Session Maintenance Requirements . . . . . . . . . . . 16 3.3.3. Message security versus session security . . . . . . . 16 4. Scenario Diagrams for the Transport Subsystem . . . . . . . . 17 4.1. Command Generator or Notification Originator . . . . . . . 17 4.2. Command Responder . . . . . . . . . . . . . . . . . . . . 18 5. Cached Information and References . . . . . . . . . . . . . . 19 5.1. securityStateReference . . . . . . . . . . . . . . . . . . 20 5.2. tmStateReference . . . . . . . . . . . . . . . . . . . . . 21 6. Abstract Service Interfaces . . . . . . . . . . . . . . . . . 21 6.1. Generating an Outgoing SNMP Message . . . . . . . . . . . 22 6.2. Processing for an Outgoing Message . . . . . . . . . . . . 23 6.3. Processing an Incoming SNMP Message . . . . . . . . . . . 23 6.3.1. Processing an Incoming Message . . . . . . . . . . . . 23 6.3.2. Prepare Data Elements from Incoming Messages . . . . . 23 6.3.3. Processing an Incoming Message . . . . . . . . . . . . 24 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 26 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 26 10.1. Normative References . . . . . . . . . . . . . . . . . . . 26 10.2. Informative References . . . . . . . . . . . . . . . . . . 27 Appendix A. Parameter Table . . . . . . . . . . . . . . . . . . . 28 A.1. ParameterList.csv . . . . . . . . . . . . . . . . . . . . 28 Appendix B. Why tmStateReference? . . . . . . . . . . . . . . . . 29 B.1. Define an Abstract Service Interface . . . . . . . . . . . 29 B.2. Using an Encapsulating Header . . . . . . . . . . . . . . 30 B.3. Modifying Existing Fields in an SNMP Message . . . . . . . 30 B.4. Using a Cache . . . . . . . . . . . . . . . . . . . . . . 30 Appendix C. Open Issues . . . . . . . . . . . . . . . . . . . . . 31 Appendix D. Change Log . . . . . . . . . . . . . . . . . . . . . 31 Harrington & Schoenwaelder Expires June 16, 2007 [Page 2] =0C Internet-Draft SNMP Transport Subsystem December 2006 1. Introduction This document describes a Transport Subsystem, extending the Simple Network Management Protocol (SNMP) architecture defined in [RFC3411]. This document identifies and discusses some key aspects that need to be considered for any transport model for SNMP. 1.1. The Internet-Standard Management Framework For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of RFC 3410 [RFC3410]. 1.2. Conventions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 2. Motivation There are multiple ways to secure one's home or business, in a continuum of alternatives. Let's consider three general approaches. In the first approach, an individual could buy a gun, learn to use it, and sit on your front porch waiting for intruders. In the second approach, one could hire an employee with a gun, schedule the employee, position the employee to guard what you want protected, hire a second guard to cover if the first gets sick, and so on. In the third approach, you could hire a security company, tell them what you want protected, and they could hire employees, train them, buy the guns, position the guards, schedule the guards, send a replacement when a guard cannot make it, etc., thus providing the security you want, with no significant effort on your part other than identifying requirements and verifying the quality of the service being provided. The User-based Security Model (USM) as defined in [RFC3414] largely uses the first approach - it provides its own security. It utilizes existing mechanisms (SHA=3Dthe gun), but provides all the = coordination. USM provides for the authentication of a principal, message encryption, data integrity checking, timeliness checking, etc. USM was designed to be independent of other existing security infrastructures. USM therefore requires a separate principal and key management infrastructure. Operators have reported that deploying another principal and key management infrastructure in order to use SNMPv3 is a deterrent to deploying SNMPv3. It is possible but difficult to define external mechanisms that handle the distribution Harrington & Schoenwaelder Expires June 16, 2007 [Page 3] =0C Internet-Draft SNMP Transport Subsystem December 2006 of keys for use by the USM approach. A solution based on the second approach might use a USM-compliant architecture, but combine the authentication mechanism with an external mechanism, such as RADIUS [RFC2865], to provide the authentication service. It might be possible to utilize an external protocol to encrypt a message, to check timeliness, to check data integrity, etc. It is difficult to cobble together a number of subcontracted services and coordinate them however, because it is difficult to build solid security bindings between the various services, and potential for gaps in the security is significant. A solution based on the third approach might utilize one or more lower-layer security mechanisms to provide the message-oriented security services required. These would include authentication of the sender, encryption, timeliness checking, and data integrity checking. There are a number of IETF standards available or in development to address these problems through security layers at the transport layer or application layer, among them TLS [RFC4366], SASL [RFC4422], and SSH [RFC4251]. From an operational perspective, it is highly desirable to use security mechanisms that can unify the administrative security management for SNMPv3, command line interfaces (CLIs) and other management interfaces. The use of security services provided by lower layers is the approach commonly used for the CLI, and is also the approach being proposed for NETCONF [I-D.ietf-netconf-ssh]. This document describes a Transport Subsystem extension to the RFC3411 architecture. Harrington & Schoenwaelder Expires June 16, 2007 [Page 4] =0C Internet-Draft SNMP Transport Subsystem December 2006 +-------------------------------------------------------------------+ | SNMP entity | | | | +-------------------------------------------------------------+ | | | SNMP engine (identified by snmpEngineID) | | | | | | | | +------------+ | | | | | Transport | | | | | | Subsystem | | | | | +------------+ | | | | | | | | +------------+ +------------+ +-----------+ +-----------+ | | | | | Dispatcher | | Message | | Security | | Access | | | | | | | | Processing | | Subsystem | | Control | | | | | | | | Subsystem | | | | Subsystem | | | | | +------------+ +------------+ +-----------+ +-----------+ | | | +-------------------------------------------------------------+ | | | | +-------------------------------------------------------------+ | | | Application(s) | | | | | | | | +-------------+ +--------------+ +--------------+ | | | | | Command | | Notification | | Proxy | | | | | | Generator | | Receiver | | Forwarder | | | | | +-------------+ +--------------+ +--------------+ | | | | | | | | +-------------+ +--------------+ +--------------+ | | | | | Command | | Notification | | Other | | | | | | Responder | | Originator | | | | | | | +-------------+ +--------------+ +--------------+ | | | +-------------------------------------------------------------+ | | | +-------------------------------------------------------------------+ This extension allows security to be provided by an external protocol connected to the SNMP engine through an SNMP transport-model [RFC3417]. Such a transport model would then enable the use of existing security mechanisms such as (TLS) [RFC4366] or SSH [RFC4251] within the RFC3411 architecture. There are a number of Internet security protocols and mechanisms that are in wide spread use. Many of them try to provide a generic infrastructure to be used by many different application layer protocols. The motivation behind the transport subsystem is to leverage these protocols where it seems useful. There are a number of challenges to be addressed to map the security Harrington & Schoenwaelder Expires June 16, 2007 [Page 5] =0C Internet-Draft SNMP Transport Subsystem December 2006 provided by a secure transport into the SNMP architecture so that SNMP continues to work without any surprises. These challenges are discussed in detail in this document. For some key issues, design choices are discussed that may be made to provide a workable solution that meets operational requirements and fits into the SNMP architecture defined in [RFC3411]. 3. Requirements of a Transport Model 3.1. Message Security Requirements Transport security protocols SHOULD ideally provide the protection against the following message-oriented threats [RFC3411]: 1. modification of information 2. masquerade 3. message stream modification 4. disclosure According to [RFC3411], it is not required to protect against denial of service or traffic analysis. 3.1.1. Security Protocol Requirements There are a number of standard protocols that could be proposed as possible solutions within the transport subsystem. Some factors should be considered when selecting a protocol. Using a protocol in a manner for which it was not designed has numerous problems. The advertised security characteristics of a protocol may depend on its being used as designed; when used in other ways, it may not deliver the expected security characteristics. It is recommended that any proposed model include a discussion of the applicability of the transport model. A transport model should require no modifications to the underlying protocol. Modifying the protocol may change its security characteristics in ways that would impact other existing usages. If a change is necessary, the change should be an extension that has no impact on the existing usages. It is recommended that any transport model include a discussion of potential impact on other usages of the protocol. It has been a long-standing requirement that SNMP be able to work when the network is unstable, to enable network troubleshooting and repair. The UDP approach has been considered to meet that need well, with an assumption that getting small messages through, even if out of order, is better than getting no messages through. There has been Harrington & Schoenwaelder Expires June 16, 2007 [Page 6] =0C Internet-Draft SNMP Transport Subsystem December 2006 a long debate about whether UDP actually offers better support than TCP when the underlying IP or lower layers are unstable. There has been recent discussion of whether operators actually use SNMP to troubleshoot and repair unstable networks. There has been discussion of ways SNMP could be extended to better support management/monitoring needs when a network is running just fine. Use of a TCP transport, for example, could enable larger message sizes and more efficient table retrievals. Transport models MUST be able to coexist with other transport models, and may be designed to utilize either TCP or UDP or SCTP. 3.2. SNMP Requirements 3.2.1. Architectural Modularity Requirements SNMP version 3 (SNMPv3) is based on a modular architecture (described in [RFC3411] section 3) to allow the evolution of the SNMP protocol standards over time, and to minimize side effects between subsystems when changes are made. The RFC3411 architecture includes a security subsystem for enabling different methods of providing security services, a messaging subsystem permitting different message versions to be handled by a single engine, an application subsystem to support different types of application processors, and an access control subsystem for allowing multiple approaches to access control. The RFC3411 architecture does not include a subsystem for transport models, despite the fact there are multiple transport mappings already defined for SNMP. This document addresses the need for a transport subsystem compatible with the RFC3411 architecture. In SNMPv2, there were many problems of side effects between subsystems caused by the manipulation of MIB objects, especially those related to authentication and authorization, because many of the parameters were stored in shared MIB objects, and different models and protocols could assign different values to the objects. Contributors assumed slightly different shades of meaning depending on the models and protocols being used. As the shared MIB module design was modified to accommodate a specific model, other models which used the same MIB objects would be broken. Abstract Service Interfaces (ASIs) were developed to pass model- independent parameters. The models were required to translate from their model-dependent formats into a model-independent format, defined using model-independent semantics, which would not impact other models. Harrington & Schoenwaelder Expires June 16, 2007 [Page 7] =0C Internet-Draft SNMP Transport Subsystem December 2006 Parameters have been provided in the ASIs to pass model-independent information about the authentication that has been provided. These parameters include a model-independent identifier of the security "principal", the security model used to perform the authentication, and which SNMP-specific security features were applied to the message (authentication and/or privacy). Parameters have been provided in the ASIs to pass model-independent transport address information. These parameters utilize the transportDomain and transportAddress The design of a transport subsystem must abide the goals of the RFC3411 architecture defined in [RFC3411]. To that end, this transport subsystem proposal uses a modular design that will permit transport models to be advanced through the standards process independently of other transport models, and independent of other modular SNMP components as much as possible. IETF standards typically require one mandatory to implement solution, with the capability of adding new mechanisms in the future. Part of the motivstion of developing transport models is to develop support for secure transport protocols, such as a transport model that utilizes the Secure Shell protocol. Any transport model should define one minimum-compliance security mechanism, preferably one which is already widely used to secure the transport layer protocol. The Transport Subsystem permits multiple transport protocols to be "plugged into" the RFC3411 architecture, supported by corresponding transport models, including models that are security-aware. The RFC3411 architecture,and the USM assume that a security model is called by a message-processing model and will perform multiple security functions within the security subsystem. A transport model that supports a secure transport protocol may perform similar security functions within the transport subsystem. A transport model may perform the translation of transport security parameters to/from security-model-independent parameters. To accommodate this, the ASIs for the transport subsystem, the messaging subsystem, and the security subsystem will be extended to pass security-model- independent values, and a cache of transport-specific information. Harrington & Schoenwaelder Expires June 16, 2007 [Page 8] =0C Internet-Draft SNMP Transport Subsystem December 2006 +------------------------------+ | Network | +------------------------------+ ^ ^ ^ | | | v v v (traditional SNMP agent) +-------------------------------------------------------------------+ | +--------------------------------------------------+ | | | Transport Subsystem | | | | +-----+ +-----+ +-----+ +-----+ +-------+ | | | | | UDP | | TCP | | SSH | | TLS | . . . | other | | | | | +-----+ +-----+ +-----+ +-----+ +-------+ | | | +--------------------------------------------------+ | | ^ | | | | | Dispatcher v | | +-------------------+ +---------------------+ +----------------+ | | | Transport | | Message Processing | | Security | | | | Dispatch | | Subsystem | | Subsystem | | | | | | +------------+ | | +------------+ | | | | | | +->| v1MP * |<--->| | USM * | | | | | | | | +------------+ | | +------------+ | | | | | | | +------------+ | | +------------+ | | | | | | +->| v2cMP * |<--->| | Transport* | | | | | Message | | | +------------+ | | | Security | | | | | Dispatch <--------->| +------------+ | | | Model | | | | | | | +->| v3MP * |<--->| +------------+ | | | | | | | +------------+ | | +------------+ | | | | PDU Dispatch | | | +------------+ | | | Other * | | | | +-------------------+ | +->| otherMP * |<--->| | Model(s) | | | | ^ | +------------+ | | +------------+ | | | | +---------------------+ +----------------+ | | v | | +-------+-------------------------+---------------+ | | ^ ^ ^ | | | | | | | v v v | | +-------------+ +---------+ +--------------+ +-------------+ | | | COMMAND | | ACCESS | | NOTIFICATION | | PROXY | | | | RESPONDER |<->| CONTROL |<->| ORIGINATOR | | FORWARDER | | | | application | | | | applications | | application | | | +-------------+ +---------+ +--------------+ +-------------+ | | ^ ^ | | | | | | v v | | +----------------------------------------------+ | | | MIB instrumentation | SNMP entity | +-------------------------------------------------------------------+ Harrington & Schoenwaelder Expires June 16, 2007 [Page 9] =0C Internet-Draft SNMP Transport Subsystem December 2006 3.2.1.1. USM and the RFC3411 Architecture The following diagrams illustrate the difference in the security processing done by the USM model and the security processing potentially done by a transport model. The USM security model is encapsulated by the messaging model, because the messaging model needs to perform the following steps (for incoming messages) 1) decode the ASN.1 (messaging model) 2) determine the SNMP security model and parameters (messaging model) 3) decrypt the encrypted portions of the message (security model) 4) translate parameters to model-independent parameters (security model) 5) determine which application should get the decrypted portions (messaging model), and 6) pass on the decrypted portions with model-independent parameters. The USM approach uses SNMP-specific message security and parameters. 3.2.1.2. Transport Subsystem and the RFC3411 Architecture With the Transport Subsystem, the order of the steps may differ and may be handled by different subsystems: 1) decrypt the encrypted portions of the message (transport layer) 2*) translate parameters to model-independent parameters (transport model) 3) determine the SNMP security model and parameters (transport model) 4) decode the ASN.1 (messaging model) 5) determine which application should get the decrypted portions (messaging model) 7) pass on the decrypted portions with model-independent security parameters If a message is secured using non-SNMP-specific message security and parameters, then the transport model should provide the translation from the authenticated identity (e.g., an SSH user name) to the securityName in step 3. 3.2.1.3. Passing Information between Engines A secure transport model will establish an encrypted tunnel between the transport models of two SNMP engines. One transport model instance encrypts all messages, and the other transport model instance decrypts the messages. After a transport layer tunnel is established, then SNMP messages can conceptually be sent through the tunnel from one SNMP engine to Harrington & Schoenwaelder Expires June 16, 2007 [Page 10] =0C Internet-Draft SNMP Transport Subsystem December 2006 another SNMP engine. Once the tunnel is established, multiple SNMP messages may be able to be passed through the same tunnel. 3.2.2. Access Control Requirements 3.2.2.1. securityName Binding For SNMP access control to function properly, security processing must establish a securityModel identifier, a securityLevel, and a securityName, which is the security model independent identifier for a principal. The message processing subsystem relies on a security model, such as USM, to play a role in security that goes beyond protecting the message - it provides a mapping between the USM- specific principal to a security-model independent securityName which can be used for subsequent processing, such as for access control. The securityName MUST be bound to the mechanism-specific authenticated identity, and this mapping MUST be done for incoming messages before the security model passes securityName to the message processing model via the processIncoming() ASI. This translation from a mechanism-specific authenticated identity to a securityName MAY be done by the transport model, and the securityname is then provided to the security model to be passed to the message processing model. If the type of authentication provided by the transport layer (e.g. TLS) is considered adequate to secure and/or encrypt the message, but inadequate to provide the desired granularity of access control (e.g. user-based), then a second authentication (e.g., one provided via a RADIUS server) MAY be used to provide the authentication identity which is bound to the securityName. This approach would require a good analysis of the potential for man-in-the-middle attacks or masquerade possibilities. 3.2.2.2. Separation of Authentication and Authorization A transport model that provides security services should take care to not violate the separation of authentication and authorization in the RFC3411 architecture. The isAccessAllowed() primitive is used for passing security-model independent parameters between the subsystems of the architecture. Mapping of (securityModel, securityName) to an access control policy should be handled within the access control subsystem, not the transport or security subsystems, to be consistent with the modularity of the RFC3411 architecture. This separation was a deliberate decision of the SNMPv3 WG, to allow support for authentication protocols which did not provide authorization Harrington & Schoenwaelder Expires June 16, 2007 [Page 11] =0C Internet-Draft SNMP Transport Subsystem December 2006 capabilities, and to support authorization schemes, such as VACM, that do not perform their own authentication. An authorization model (in the access control subsystem) MAY require authentication by certain securityModels and a minimum securityLevel to allow access to the data. Transport models that provide secure transport are an enhancement for the SNMPv3 privacy and authentication, but they are not a significant improvement for the authorization (access control) needs of SNMPv3. Only the model-independent parameters for the isAccessAllowed() primitive [RFC3411] are provided by the transport and security subsystems. A transport model must not specify how the securityModel and securityName could be dynamically mapped to an access control mechanism, such as a VACM-style groupName. The mapping of (securityModel, securityName) to a groupName is a VACM-specific mechanism for naming an access control policy, and for tying the named policy to the addressing capabilities of the data modeling language (e.g. SMIv2 [RFC2578]), the operations supported, and other factors. Providing a binding outside the Access Control subsystem might create dependencies that could make it harder to develop alternate models of access control, such as one built on UNIX groups or Windows domains. The preferred approach is to pass the model- independent security parameters via the isAccessAllowed() ASI, and perform the mapping from the model-independent security parameters to an authorization-model-dependent access policy within the access control model. To provide support for protocols which simultaneously send information for authentication and authorization, such as RADIUS [RFC2865], model-specific authorization information MAY be cached or otherwise made available to the access control subsystem, e.g., via a MIB table similar to the vacmSecurityToGroupTable, so the access control subsystem can create an appropriate binding between the model-independent securityModel and securityName and a model-specific access control policy. This may be highly undesirable, however, if it creates a dependency between a transport model or a security model and an access control model, just as it is undesirable for a transport model to create a dependency between an SNMP message version and the security provided by a transport model. 3.2.3. Security Parameter Passing Requirements RFC3411 section 4 describes primitives to describe the abstract data flows between the various subsystems, models and applications within the architecture. Abstract Service Interfaces describe the flow of Harrington & Schoenwaelder Expires June 16, 2007 [Page 12] =0C Internet-Draft SNMP Transport Subsystem December 2006 data between subsystems within an engine. The ASIs generally pass model-independent information. Within an engine using a transport model, outgoing SNMP messages are passed unencrypted from the message dispatcher to the transport model, and incoming messages are passed unencrypted from the transport model to the message dispatcher. The security parameters include a model-independent identifier of the security "principal", the security model used to perform the authentication, and which SNMP-specific security services were (should be) applied to the message (authentication and/or privacy). In the RFC3411 architecture, which reflects the USM security model design, the messaging model must unpack SNMP-specific security parameters from an incoming message before calling a specific security model to authenticate and decrypt an incoming message, perform integrity checking, and translate model-specific security parameters into model-independent parameters. When using a secure transport model, security parameters MAY be provided through means other than carrying them in the SNMP message. The parameters MAY be provided by SNMP applications for outgoing messages, and the parameters for incoming messages MAY be extracted from the transport layer by the transport model before the message is passed to the message processing subsystem. For outgoing messages, even when a secure transport model will provide the security services, it is necessary to have an security model because it is the security model that actually creates the message from its component parts. Whether there are any security services provided by the security model for an outgoing message is model-dependent. For incoming messages, even when a secure transport model provides security services, a security model is necessary because there might be some security functionality that can only be provided after the message version is known. The message version is determined by the Message Processing model and passed to the security model via the processIncoming() ASI. The RFC3411 architecture has no ASI parameters for passing security information between a transport mapping (a transport model) and the dispatcher, and between the dispatcher and the message processing model. This document describes a cache mechanism, into which the transport model puts information about the transport and security parameters Harrington & Schoenwaelder Expires June 16, 2007 [Page 13] =0C Internet-Draft SNMP Transport Subsystem December 2006 applied to a transport connection or an incoming message, and a security model MAY extract that information from the cache. A tmStateReference is passed as an extra parameter in the ASIs of the transport subsystem and the messaging and security subsystems, to identify the relevant cache. This approach of passing a model-independent reference is consistent with the securityStateReference cache already being passed around in the RFC3411 ASIs. 3.3. Session Requirements Some secure transports may have a notion of sessions, while other secure transports might provide channels or other session-like thing. Throughout this document, the term session is used in a broad sense to cover sessions, channels, and session-like things. Session refers to an association between two SNMP engines that permits the transmission of one or more SNMP messages within the lifetime of the session. How the session is actually established, opened, closed, or maintained is specific to a particular transport model. Sessions are not part of the SNMP architecture described in [RFC3411], but are considered desirable because the cost of authentication can be amortized over potentially many transactions. It is important to note that the architecture described in [RFC3411] does not include a session selector in the Abstract Service Interfaces, and neither is that done for the transport subsystem, so an SNMP application cannot select the session except by passing a unique combination of transport type, transport address, securityName, securityModel, and securityLevel. All transport models should discuss the impact of sessions on SNMP usage, including how to establish/open a transport session (i.e., how it maps to the concepts of session-like things of the underlying protocol), how to behave when a session cannot be established, how to close a session properly, how to behave when a session is closed improperly, the session security properties, session establishment overhead, and session maintenance overhead. To reduce redundancy, this document will discuss aspects that are expected to be common to all transport model sessions. 3.3.1. Session Establishment Requirements SNMP applications must provide the transport type, transport address, securityName, securityModel, and securityLevel to be used for a session. Harrington & Schoenwaelder Expires June 16, 2007 [Page 14] =0C Internet-Draft SNMP Transport Subsystem December 2006 SNMP Applications typically have no knowledge of whether the session that will be used to carry commands was initially established as a notification session, or a request-response session, and SHOULD NOT make any assumptions based on knowing the direction of the session. If an administrator or transport model designer wants to differentiate a session established for different purposes, such as a notification session versus a request-response session, the application can use different securityNames or transport addresses (e.g., port 161 vs. port 162) for different purposes. An SNMP engine containing an application that initiates communication, e.g., a Command Generator or Notification Originator, MUST be able to attempt to establish a session for delivery if a session does not yet exist. If a session cannot be established then the message is discarded. Sessions are usually established by the transport model when no appropriate session is found for an outgoing message, but sessions may be established in advance to support features such as notifications. How sessions are established in advance is beyond the scope of this document. Sessions are initiated by notification originators when there is no currently established connection that can be used to send the notification. For a client-server security protocol, this may require provisioning authentication credentials on the agent, either statically or dynamically, so the client/agent can successfully authenticate to a notification receiver. A transport model must be able to determine whether a session does or does not exist, and must be able to determine which session has the appropriate security characteristics (transport type, transport address, securityName, securityModel, and securityLevel) for an outgoing message. A transport model implementation MAY reuse an already established session with the appropriate transport type, transport address, securityName, securityModel, and securityLevel characteristics for delivery of a message originated by a different type of application than originally caused the session to be created. For example, an implementation that has an existing session originally established to receive a request may use that session to send an outgoing notification, and may use a session that was originally established to send a notification to send a request. Responses are expected to be returned using the same session that carried the corresponding request message. Reuse of sessions is not required for conformance. If a session can be reused for a different type of message, but a Harrington & Schoenwaelder Expires June 16, 2007 [Page 15] =0C Internet-Draft SNMP Transport Subsystem December 2006 receiver is not prepared to accept different message types over the same session, then the message MAY be dropped by the receiver. This may strongly affect the usefulness of session reuse, and transport models should define a standard behavior for this circumstance. 3.3.2. Session Maintenance Requirements A transport model can tear down sessions as needed. It may be necessary for some implementations to tear down sessions as the result of resource constraints, for example. The decision to tear down a session is implementation-dependent. While it is possible for an implementation to automatically tear down each session once an operation has completed, this is not recommended for anticipated performance reasons. How an implementation determines that an operation has completed, including all potential error paths, is implementation-dependent. The elements of procedure may discuss when cached information can be discarded, and the timing of cache cleanup may have security implications, but cache memory management is an implementation issue. If a transport model defines MIB module objects to maintain session state information, then the transport model MUST describe what happens to the objects when a related session is torn down, since this will impact interoperability of the MIB module. 3.3.3. Message security versus session security A transport model session is associated with state information that is maintained for its lifetime. This state information allows for the application of various security services to multiple messages. Cryptographic keys established at the beginning of the session SHOULD be used to provide authentication, integrity checking, and encryption services for data that is communicated during the session. The cryptographic protocols used to establish keys for a transport model session SHOULD ensure that fresh new session keys are generated for each session. If each session uses new session keys, then messages cannot be replayed from one session to another. In addition sequence information MAY be maintained in the session which can be used to prevent the replay and reordering of messages within a session. A transport model session will typically have a single transport type, transport address, securityModel, securityName and securityLevel associated with it. If an exchange between communicating engines requires a different securityLevel or is on behalf of a different securityName, or uses a different securityModel, then another session would be needed. An immediate Harrington & Schoenwaelder Expires June 16, 2007 [Page 16] =0C Internet-Draft SNMP Transport Subsystem December 2006 consequence of this is that implementations should be able to maintain some reasonable number of concurrent sessions. For transport models, securityName is typically specified during session setup, and associated with the session identifier. SNMPv3 was designed to support multiple levels of security, selectable on a per-message basis by an SNMP application, because there is not much value in using encryption for a Commander Generator to poll for non-sensitive performance data on thousands of interfaces every ten minutes; the encryption may add significant overhead to processing of the messages. Some transport models MAY support only specific authentication and encryption services, such as requiring all messages to be carried using both authentication and encryption, regardless of the security level requested by an SNMP application. A transport model MAY upgrade the requested security level, i.e. noAuth/noPriv and auth/ noPriv MAY be sent over an authenticated and encrypted session. 4. Scenario Diagrams for the Transport Subsystem RFC3411 section 4.6 provides scenario diagrams to illustrate how an outgoing message is created, and how an incoming message is processed. Both diagrams are incomplete, however. In section 4.6.1, the diagram doesn't show the ASI for sending an SNMP request to the network or receiving an SNMP response message from the network. In section 4.6.2, the diagram doesn't illustrate the interfaces required to receive an SNMP message from the network, or to send an SNMP message to the network. 4.1. Command Generator or Notification Originator This diagram from RFC3411 4.6.1 shows how a Command Generator or Notification Originator application [RFC3413] requests that a PDU be sent, and how the response is returned (asynchronously) to that application. Harrington & Schoenwaelder Expires June 16, 2007 [Page 17] =0C Internet-Draft SNMP Transport Subsystem December 2006 Command Dispatcher Message Security Generator | Processing Model | | Model | | sendPdu | | | |------------------->| | | | | prepareOutgoingMessage | | : |----------------------->| | : | | generateRequestMsg | : | |-------------------->| : | | | : | |<--------------------| : | | | : |<-----------------------| | : | | | : |------------------+ | | : | Send SNMP | | | : | Request Message | | | : | to Network | | | : | v | | : : : : : : : : : : : : : : : : | | | | : | Receive SNMP | | | : | Response Message | | | : | from Network | | | : |<-----------------+ | | : | | | : | prepareDataElements | | : |----------------------->| | : | | processIncomingMsg | : | |-------------------->| : | | | : | |<--------------------| : | | | : |<-----------------------| | | processResponsePdu | | | |<-------------------| | | | | | | 4.2. Command Responder This diagram shows how a Command Responder or Notification Receiver application registers for handling a pduType, how a PDU is dispatched to the application after an SNMP message is received, and how the Response is (asynchronously) send back to the network. Harrington & Schoenwaelder Expires June 16, 2007 [Page 18] =0C Internet-Draft SNMP Transport Subsystem December 2006 Command Dispatcher Message Security Responder | Processing Model | | Model | | | | | | registerContextEngineID | | | |------------------------>| | | |<------------------------| | | | | | Receive SNMP | | | : | Message | | | : | from Network | | | : |<-------------+ | | : | | | : |prepareDataElements | | : |------------------->| | : | | processIncomingMsg | : | |------------------->| : | | | : | |<-------------------| : | | | : |<-------------------| | | processPdu | | | |<------------------------| | | | | | | : : : : : : : : | returnResponsePdu | | | |------------------------>| | | : | prepareResponseMsg | | : |------------------->| | : | |generateResponseMsg | : | |------------------->| : | | | : | |<-------------------| : | | | : |<-------------------| | : | | | : |--------------+ | | : | Send SNMP | | | : | Message | | | : | to Network | | | : | v | | 5. Cached Information and References The RFC3411 architecture uses caches to store dynamic model-specific information, and uses references in the ASIs to indicate in a model- independent manner which cached information must flow between Harrington & Schoenwaelder Expires June 16, 2007 [Page 19] =0C Internet-Draft SNMP Transport Subsystem December 2006 subsystems. There are two levels of state that may need to be maintained: the security state in a request-response pair, and potentially long-term state relating to transport and security. This state is maintained in caches. To simplify the elements of procedure, the release of state information is not always explicitly specified. As a general rule, if state information is available when a message being processed gets discarded, the state related to that message should also be discarded, and if state information is available when a relationship between engines is severed, such as the closing of a transport session, the state information for that relationship might also be discarded. This document differentiates the tmStateReference from the securityStateReference. This document does not specify an implementation strategy, only an abstract discussion of the data that must flow between subsystems. An implementation MAY use one cache and one reference to serve both functions, but an implementer must be aware of the cache-release issues to prevent the cache from being released before a security or transport model has had an opportunity to extract the information it needs. 5.1. securityStateReference From RFC3411: "For each message received, the Security Model caches the state information such that a Response message can be generated using the same security information, even if the Local Configuration Datastore is altered between the time of the incoming request and the outgoing response. A Message Processing Model has the responsibility for explicitly releasing the cached data if such data is no longer needed. To enable this, an abstract securityStateReference data element is passed from the Security Model to the Message Processing Model. The cached security data may be implicitly released via the generation of a response, or explicitly released by using the stateRelease primitive, as described in RFC3411 section 4.5.1." The information saved should include the model-independent parameters (transportDomain, transportAddress, securityName, securityModel, and securityLevel), related security parameters, and other information needed to imatch the response with the request. The Message Processing Model has the responsibility for explicitly releasing the securityStateReference when such data is no longer needed. The securityStateReference cached data may be implicitly released via the generation of a response, or explicitly released by using the Harrington & Schoenwaelder Expires June 16, 2007 [Page 20] =0C Internet-Draft SNMP Transport Subsystem December 2006 stateRelease primitive, as described in RFC 3411 section 4.5.1." If the transport model connection is closed between the time a Request is received and a Response message is being prepared, then the Response message MAY be discarded. 5.2. tmStateReference For each message or transport session, information about the message security is stored in a cache, which may inlcude model- and mechanism-specific parameters. The tmStateReference is passed between subsystems to provide a handle for the cache. A transport model may store transport-specific parameters in the cache for subsequent usage. Since the contents of a cache are meaningful only within an implementation, and not on-the-wire, the format of the cache is implementation-specific. The state referenced by tmStateReference may be saved in a Local Configuration Datastore (LCD) to make it available across multiple messages, as compared to securityStateReference which is designed to be saved only for the life of a request-response pair of messages. It is expected that an LCD will allow lookup based on the combination of transportDomain, transportAddress, securityName, securityModel, and securityLevel, and that the cache contain these values to reference entries in the LCD. 6. Abstract Service Interfaces Abstract service interfaces have been defined by RFC 3411 to describe the conceptual data flows between the various subsystems within an SNMP entity. To simplify the elements of procedure, the release of state information is not always explicitly specified. As a general rule, if state information is available when a message gets discarded, the message-state information should also be released, and if state information is available when a session is closed, the session state information should also be released. An error indication may return an OID and value for an incremented counter and a value for securityLevel, and values for contextEngineID and contextName for the counter, and the securityStateReference if the information is available at the point where the error is detected. Harrington & Schoenwaelder Expires June 16, 2007 [Page 21] =0C Internet-Draft SNMP Transport Subsystem December 2006 6.1. Generating an Outgoing SNMP Message This section describes the procedure followed by an RFC3411- compatible system whenever it generates a message containing a management operation (such as a request, a response, a notification, or a report) on behalf of a user. statusInformation =3D -- success or errorIndication prepareOutgoingMessage( IN transportDomain -- transport domain to be used IN transportAddress -- transport address to be used IN messageProcessingModel -- typically, SNMP version IN securityModel -- Security Model to use IN securityName -- on behalf of this principal IN securityLevel -- Level of Security requested IN contextEngineID -- data from/at this entity IN contextName -- data from/in this context IN pduVersion -- the version of the PDU IN PDU -- SNMP Protocol Data Unit IN expectResponse -- TRUE or FALSE IN sendPduHandle -- the handle for matching incoming responses OUT destTransportDomain -- destination transport domain OUT destTransportAddress -- destination transport address OUT outgoingMessage -- the message to send OUT outgoingMessageLength -- its length OUT tmStateReference -- (NEW) reference to transport state ) Note that tmStateReference has been added to this ASI. The IN parameters of the prepareOutgoingMessage() ASI are used to pass information from the dispatcher (from the application subsystem) to the message processing subsystem. The abstract service primitive from a Message Processing Model to a Security Model to generate the components of a Request message is generateRequestMsg(). The abstract service primitive from a Message Processing Model to a Security Model to generate the components of a Response message is generateResponseMsg(). Upon completion of processing, the Security Model returns statusInformation. If the process was successful, the completed message is returned. If the process was not successful, then an errorIndication is returned. Harrington & Schoenwaelder Expires June 16, 2007 [Page 22] =0C Internet-Draft SNMP Transport Subsystem December 2006 The OUT parameters of the prepareOutgoingMessage() ASI are used to pass information from the message processing model to the dispatcher and on to the transport model: 6.2. Processing for an Outgoing Message The sendMessage ASI is used to pass a message from the Dispatcher to the appropriate transport model for sending. statusInformation =3D sendMessage( IN destTransportDomain -- transport domain to be used IN destTransportAddress -- transport address to be used IN outgoingMessage -- the message to send IN outgoingMessageLength -- its length IN tmStateReference -- reference to transport state ) 6.3. Processing an Incoming SNMP Message 6.3.1. Processing an Incoming Message If one does not exist, the Transport Model will need to create an entry in a Local Configuration Datastore referenced by tmStateReference. This information will include transportDomain, transportAddress, the securityModel, the securityLevel, and the securityName, plus any model or mechanism-specific details. How this information is determined is model-specific. The recvMessage ASI is used to pass a message from the transport subsystem to the Dispatcher. statusInformation =3D recvMessage( IN transportDomain -- origin transport domain IN transportAddress -- origin transport address IN incomingMessage -- the message received IN incomingMessageLength -- its length IN tmStateReference -- reference to transport state ) 6.3.2. Prepare Data Elements from Incoming Messages The abstract service primitive from the Dispatcher to a Message Processing Model for a received message is: Harrington & Schoenwaelder Expires June 16, 2007 [Page 23] =0C Internet-Draft SNMP Transport Subsystem December 2006 result =3D -- SUCCESS or errorIndication prepareDataElements( IN transportDomain -- origin transport domain IN transportAddress -- origin transport address IN wholeMsg -- as received from the network IN wholeMsgLength -- as received from the network IN tmStateReference -- (NEW) from the transport model OUT messageProcessingModel -- typically, SNMP version OUT securityModel -- Security Model to use OUT securityName -- on behalf of this principal OUT securityLevel -- Level of Security requested OUT contextEngineID -- data from/at this entity OUT contextName -- data from/in this context OUT pduVersion -- the version of the PDU OUT PDU -- SNMP Protocol Data Unit OUT pduType -- SNMP PDU type OUT sendPduHandle -- handle for matched request OUT maxSizeResponseScopedPDU -- maximum size sender can accept OUT statusInformation -- success or errorIndication -- error counter OID/value if error OUT stateReference -- reference to state information -- to be used for possible Response ) Note that tmStateReference has been added to this ASI. 6.3.3. Processing an Incoming Message This section describes the procedure followed by the Security Model whenever it receives an incoming message containing a management operation on behalf of a user from a Message Processing model. The Message Processing Model extracts some information from the wholeMsg. The abstract service primitive from a Message Processing Model to the Security Subsystem for a received message is: Harrington & Schoenwaelder Expires June 16, 2007 [Page 24] =0C Internet-Draft SNMP Transport Subsystem December 2006 statusInformation =3D -- errorIndication or success -- error counter OID/value if error processIncomingMsg( IN messageProcessingModel -- typically, SNMP version IN maxMessageSize -- of the sending SNMP entity IN securityParameters -- for the received message IN securityModel -- for the received message IN securityLevel -- Level of Security IN wholeMsg -- as received on the wire IN wholeMsgLength -- length as received on the wire IN tmStateReference -- (NEW) from the transport model OUT securityEngineID -- authoritative SNMP entity OUT securityName -- identification of the principal OUT scopedPDU, -- message (plaintext) payload OUT maxSizeResponseScopedPDU -- maximum size sender can handle OUT securityStateReference -- reference to security state ) -- information, needed for response 1) The securityEngineID is set to a value in a model-specific manner. If the securityEngineID is not utilized by the specific model, then it should be set to the local snmpEngineID, to satisfy the SNMPv3 message processing model in RFC 3412 section 7.2 13a). 2) Extract the value of securityName from the Local Configuration Datastore entry referenced by tmStateReference. 3) The scopedPDU component is extracted from the wholeMsg. 4) The maxSizeResponseScopedPDU is calculated. This is the maximum size allowed for a scopedPDU for a possible Response message. 5) The security data is cached as cachedSecurityData, so that a possible response to this message can and will use the same security parameters. Then securityStateReference is set for subsequent reference to this cached data. 6) The statusInformation is set to success and a return is made to the calling module passing back the OUT parameters as specified in the processIncomingMsg primitive. 7. Security Considerations This document describes an architectural approach that would permit SNMP to utilize transport layer security services. Each proposed transport model should discuss the security considerations of the transport model. It is considered desirable by some industry segments that SNMP Harrington & Schoenwaelder Expires June 16, 2007 [Page 25] =0C Internet-Draft SNMP Transport Subsystem December 2006 transport models should utilize transport layer security that addresses perfect forward secrecy at least for encryption keys. Perfect forward secrecy guarantees that compromise of long term secret keys does not result in disclosure of past session keys. The editors recommend that each proposed transport model include a discussion in its security considerations of whether perfect forward security is appropriate for the transport model. Since the cache and LCD will contain security-related parameters, they should be kept in protected storage. 8. IANA Considerations This document requires no action by IANA. 9. Acknowledgments The Integrated Security for SNMP WG would like to thank the following people for their contributions to the process: The authors of submitted security model proposals: Chris Elliot, Wes Hardaker, Dave Harrington, Keith McCloghrie, Kaushik Narayan, Dave Perkins, Joseph Salowey, and Juergen Schoenwaelder. The members of the Protocol Evaluation Team: Uri Blumenthal, Lakshminath Dondeti, Randy Presuhn, and Eric Rescorla. WG members who committed to and performed detailed reviews: Jeffrey Hutzelman 10. References 10.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2578] McCloghrie, K., Ed., Perkins, D., Ed., and J. Schoenwaelder, Ed., "Structure of Management Information Version 2 (SMIv2)", STD 58, RFC 2578, April 1999. [RFC3411] Harrington, D., Presuhn, R., and B. Wijnen, "An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks", STD 62, RFC 3411, December 2002. Harrington & Schoenwaelder Expires June 16, 2007 [Page 26] =0C Internet-Draft SNMP Transport Subsystem December 2006 [RFC3412] Case, J., Harrington, D., Presuhn, R., and B. Wijnen, "Message Processing and Dispatching for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3412, December 2002. [RFC3414] Blumenthal, U. and B. Wijnen, "User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3)", STD 62, RFC 3414, December 2002. [RFC3417] Presuhn, R., "Transport Mappings for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3417, December 2002. 10.2. Informative References [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, June 2000. [RFC3410] Case, J., Mundy, R., Partain, D., and B. Stewart, "Introduction and Applicability Statements for Internet-Standard Management Framework", RFC 3410, December 2002. [RFC3413] Levi, D., Meyer, P., and B. Stewart, "Simple Network Management Protocol (SNMP) Applications", STD 62, RFC 3413, December 2002. [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and T. Wright, "Transport Layer Security (TLS) Extensions", RFC 4366, April 2006. [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and Security Layer (SASL)", RFC 4422, June 2006. [RFC4251] Ylonen, T. and C. Lonvick, "The Secure Shell (SSH) Protocol Architecture", RFC 4251, January 2006. [I-D.ietf-netconf-ssh] Wasserman, M. and T. Goddard, "Using the NETCONF Configuration Protocol over Secure Shell (SSH)", draft-ietf-netconf-ssh-06 (work in progress), March 2006. Harrington & Schoenwaelder Expires June 16, 2007 [Page 27] =0C Internet-Draft SNMP Transport Subsystem December 2006 Appendix A. Parameter Table Following is a CSV formatted matrix useful for tracking data flows into and out of the dispatcher, transport, message, and security subsystems. Import this into your favorite spreadsheet or other CSV compatible application. You will need to remove lines feeds from the second, third, and fourth lines, which needed to be wrapped to fit into RFC limits. A.1. ParameterList.csv ,Dispatcher,,,,Messaging,,,Security,,,Transport, ,sendPDU,returnResponse,processPDU,processResponse, prepareOutgoingMessage,prepareResponseMessage,prepareDataElements, generateRequest,processIncoming,generateResponse, sendMessage,recvMessage transportDomain,In,,,,In,,In,,,,,In transportAddress,In,,,,In,,In,,,,,In destTransportDomain,,,,,Out,Out,,,,,In, destTransportAddress,,,,,Out,Out,,,,,In, messageProcessingModel,In,In,In,In,In,In,Out,In,In,In,, securityModel,In,In,In,In,In,In,Out,In,In,In,, securityName,In,In,In,In,In,In,Out,In,Out,In,, securityLevel,In,In,In,In,In,In,Out,In,In,In,, contextEngineID,In,In,In,In,In,In,Out,,,,, contextName,In,In,In,In,In,In,Out,,,,, expectResponse,In,,,,In,,,,,,, PDU,In,In,In,In,In,In,Out,,,,, pduVersion,In,In,In,In,In,In,Out,,,,, statusInfo,Out,In,,In,,In,Out,Out,Out,Out,, Harrington & Schoenwaelder Expires June 16, 2007 [Page 28] =0C Internet-Draft SNMP Transport Subsystem December 2006 errorIndication,Out,Out,,,,,Out,,,,, sendPduHandle,Out,,,In,In,,Out,,,,, maxSizeResponsePDU,,In,In,,,In,Out,,Out,,, stateReference,,In,In,,,In,Out,,,,, wholeMessage,,,,,Out,Out,In,Out,In,Out,In,In messageLength,,,,,Out,Out,In,Out,In,Out,In,In maxMessageSize,,,,,,,,In,In,In,, globalData,,,,,,,,In,,In,, securityEngineID,,,,,,,,In,Out,In,, scopedPDU,,,,,,,,In,Out,In,, securityParameters,,,,,,,,Out,In,Out,, securityStateReference,,,,,,,,,Out,In,, pduType,,,,,,,Out,,,,, tmStateReference,,,,,Out,Out,In,,In,,In,In Appendix B. Why tmStateReference? This appendix considers why a cache-based approach was selected for passing parameters. This section may be removed from subsequent revisions of the document. There are four approaches that could be used for passing information between the Transport Model and an Security Model. 1. one could define an ASI to supplement the existing ASIs, or 2. one could add a header to encapsulate the SNMP message, 3. one could utilize fields already defined in the existing SNMPv3 message, or 4. one could pass the information in an implementation-specific cache or via a MIB module. B.1. Define an Abstract Service Interface Abstract Service Interfaces (ASIs) [RFC3411] are defined by a set of primitives that specify the services provided and the abstract data Harrington & Schoenwaelder Expires June 16, 2007 [Page 29] =0C Internet-Draft SNMP Transport Subsystem December 2006 elements that are to be passed when the services are invoked. Defining additional ASIs to pass the security and transport information from the transport subsystem to security subsystem has the advantage of being consistent with existing RFC3411/3412 practice, and helps to ensure that any transport model proposals pass the necessary data, and do not cause side effects by creating model- specific dependencies between itself and other models or other subsystems other than those that are clearly defined by an ASI. B.2. Using an Encapsulating Header A header could encapsulate the SNMP message to pass necessary information from the Transport Model to the dispatcher and then to a messaging security model. The message header would be included in the wholeMessage ASI parameter, and would be removed by a corresponding messaging model. This would imply the (one and only) messaging dispatcher would need to be modified to determine which SNMP message version was involved, and a new message processing model would need to be developed that knew how to extract the header from the message and pass it to the Security Model. B.3. Modifying Existing Fields in an SNMP Message [RFC3412] describes the SNMPv3 message, which contains fields to pass security related parameters. The transport subsystem could use these fields in an SNMPv3 message, or comparable fields in other message formats to pass information between transport models in different SNMP engines, and to pass information between a transport model and a corresponding messaging security model. If the fields in an incoming SNMPv3 message are changed by the Transport Model before passing it to the Security Model, then the Transport Model will need to decode the ASN.1 message, modify the fields, and re-encode the message in ASN.1 before passing the message on to the message dispatcher or to the transport layer. This would require an intimate knowledge of the message format and message versions so the Transport Model knew which fields could be modified. This would seriously violate the modularity of the architecture. B.4. Using a Cache This document describes a cache, into which the Transport Model puts information about the security applied to an incoming message, and a Security Model can extract that information from the cache. Given that there may be multiple TM-security caches, a tmStateReference is passed as an extra parameter in the ASIs between the transport subsystem and the security subsystem, so the Security Model knows which cache of information to consult. Harrington & Schoenwaelder Expires June 16, 2007 [Page 30] =0C Internet-Draft SNMP Transport Subsystem December 2006 This approach does create dependencies between a specific Transport Model and a corresponding specific Security Model. However, the approach of passing a model-independent reference to a model- dependent cache is consistent with the securityStateReference already being passed around in the RFC3411 ASIs. Appendix C. Open Issues Appendix D. Change Log NOTE to RFC editor: Please remove this change log before publishing this document as an RFC. Changes from revision -04- to -05- removed all objects from the MIB module. changed document status to "Standard" rather than the xml2rfc default of informational. changed mention of MD5 to SHA moved addressing style to TDomain and TAddress modified the diagrams as requested removed the "layered stack" diagrams that compared USM and a Transport Model processing removed discussion of speculative features that might exist in future transport models removed openSession() and closeSession() ASIs, since those are model-dependent removed the MIB module removed the MIB boilerplate into (this memo defines a SMIv2 MIB ...) removed IANA considerations related to the now-gone MIB module removed security considerations related to the MIB module removed references needed for the MIB module changed recvMessage ASI to use origin transport domain/address updated Parameter CSV appendix Changes from revision -03- to -04- changed title from Transport Mapping Security Model Architectural Extension to Transport Subsystem modified the abstract and introduction changed TMSM to TMS changed MPSP to simply Security Model changed SMSP to simply Security Model changed TMSP to Transport Model removed MPSP and TMSP and SMSP from Acronyms section Harrington & Schoenwaelder Expires June 16, 2007 [Page 31] =0C Internet-Draft SNMP Transport Subsystem December 2006 modified diagrams removed most references to dispatcher functionality worked to remove dependencies between transport and security models. defined snmpTransportModel enumeration similar to snmpSecurityModel, etc. eliminated all reference to SNMPv3 msgXXXX fields changed tmSessionReference back to tmStateReference Changes from revision -02- to -03- o removed session table from MIB module o removed sessionID from ASIs o reorganized to put ASI discussions in EOP section, as was done in SSHSM o changed user auth to client auth o changed tmStateReference to tmSessionReference o modified document to meet consensus positions published by JS o * authoritative is model-specific * msgSecurityParameters usage is model-specific * msgFlags vs. securityLevel is model/implementation-specific * notifications must be able to cause creation of a session * security considerations must be model-specific * TDomain and TAddress are model-specific * MPSP changed to SMSP (Security model security processing) Changes from revision -01- to -02- o wrote text for session establishment requirements section. o wrote text for session maintenance requirements section. o removed section on relation to SNMPv2-MIB o updated MIB module to pass smilint o Added Structure of the MIB module, and other expected MIB-related sections. o updated author address o corrected spelling o removed msgFlags appendix o Removed section on implementation considerations. o started modifying the security boilerplate to address TMS and MIB security issues o reorganized slightly to better separate requirements from proposed solution. This probably needs additional work. o removed section with sample protocols and sample tmSessionReference. o Added section for acronyms Harrington & Schoenwaelder Expires June 16, 2007 [Page 32] =0C Internet-Draft SNMP Transport Subsystem December 2006 o moved section comparing parameter passing techniques to appendix. o Removed section on notification requirements. Changes from revision -00- o changed SSH references from I-Ds to RFCs o removed parameters from tmSessionReference for DTLS that revealed lower layer info. o Added TMS-MIB module o Added Internet-Standard Management Framework boilerplate o Added Structure of the MIB Module o Added MIB security considerations boilerplate (to be completed) o Added IANA Considerations o Added ASI Parameter table o Added discussion of Sessions o Added Open issues and Change Log o Rearranged sections Authors' Addresses David Harrington Huawei Technologies (USA) 1700 Alma Dr. Suite 100 Plano, TX 75075 USA Phone: +1 603 436 8634 EMail: dharrington@huawei.com Juergen Schoenwaelder International University Bremen Campus Ring 1 28725 Bremen Germany Phone: +49 421 200-3587 EMail: j.schoenwaelder@iu-bremen.de Harrington & Schoenwaelder Expires June 16, 2007 [Page 33] =0C Internet-Draft SNMP Transport Subsystem December 2006 Full Copyright Statement Copyright (C) The IETF Trust (2006). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgement Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Harrington & Schoenwaelder Expires June 16, 2007 [Page 34] =0C ------=_NextPart_000_1414_01C71EE7.583A4180 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms ------=_NextPart_000_1414_01C71EE7.583A4180-- From isms-bounces@lists.ietf.org Thu Dec 14 02:07:28 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GukgW-0006MO-W0; Thu, 14 Dec 2006 02:07:16 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GukgV-0006Ly-Kc for isms@ietf.org; Thu, 14 Dec 2006 02:07:15 -0500 Received: from ipmail01.adl2.internode.on.net ([203.16.214.140]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GukgS-00021l-V5 for isms@ietf.org; Thu, 14 Dec 2006 02:07:15 -0500 Received: from ppp36-69.lns2.syd6.internode.on.net (HELO wattle.kardinia.com) ([59.167.36.69]) by ipmail01.adl2.internode.on.net with ESMTP; 14 Dec 2006 17:37:07 +1030 X-IronPort-AV: i="4.12,166,1165152600"; d="scan'208"; a="61513460:sNHT22570821" Message-Id: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> X-Sender: joe.fernandez@mail.internode.on.net X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Thu, 14 Dec 2006 18:05:09 +1100 To: isms@ietf.org From: Joe Fernandez Subject: Re: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] In-Reply-To: <20061213212359.GA4888@boskop.local> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Spam-Score: 0.1 (/) X-Scan-Signature: 287c806b254c6353fcb09ee0e53bbc5e Cc: X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, At 10:23 PM 13-12-06 +0100, Juergen Schoenwaelder wrote: >I started an ID concerning engineID discovery. >I am looking for review, feedback, criticism and suggestions. I have one major question and a few minor ones that are numbered below. The question is about registration and Abstract Service Interfaces. RFC 3411 calls itself an architecture for *describing* SNMP Management Frameworks and I take this to mean it should not be interpreted as the *required* architecture for *implementing* SNMP Management Frameworks. The standard specifies what goes on the wire, not what goes in the box, right? Designers can consent to their modules doing different things in the privacy of their own nodes. RFC 3411 introduces ASIs and says they "are intended to help clarify the externally observable behavior of SNMP entities, and are not intended to constrain the structure or organization of implementations in any way." The ASIs introduce the concept of applications registering responsibility for contexts. With this background, my question is whether your procedure which seems to specify that applications have to register in a particular way, is constraining the implementation in a way that was not originally intended. It seems to me that the alternative of recognizing a local context constant does not unduly constrain the implementation to the ASIs. As part of this question, I would like to ask David Harrington: With reference to your recent posting in which you described the ASIs as highly unpopular, can you say with whom they are unpopular and why? Minor questions: 1. Section 3.1 says "To facilitate discovery, it is assumed that SNMP agents register their snmpEngineID scalar using a special well known contextEngineID.". I find the wording - "assumed" - odd. Don't you need to say something along the lines: This (standard/specification/whatever) requires an SNMP agent to register its snmpEngineID using a special well known contextEngineID, which is defined later in this document and/or the SNMP Framework MIB." or "..an SNMP agent MUST register....." ? 2. Section 3.1 says that agent implementations MAY register other objects with the localEngineID but managers should not count on it. How does the manager discover which way the implementer has chosen to go (short of trial and error)? 3. I know what your pseudo code is meant to do because we have discussed it (at some length :-) ) But isn't a new reader going to be baffled by the code first setting contextEngineID to the localEngineID constant and then immediately again setting it? There's no ASI here to tell the reader that the constant is used in the Get. I suggest that you may want to add comments to this block of pseudo code. 4 Assorted editorial: 4.a Section 1: To retrieve management information using the third version of the Simple Network Management Protocol (SNMPv3) [RFC3410], it is necessary to know the identifier of the remote SNMP protocol engine. engineID is also needed for setting. 4.b Section 3: when you say " ..require the snmpEngineID scalar" do you mean "request" or "acquire", perhaps? 4.c. Section 3.1 Some of the references to "agent" may need to be "command responder application" - ? 4.d Section 4. Thank you for the generous acknowledgement. It seems curmudgeonly to offer a correction but since we have been warned of the problems with using slang and idiom, I'll suggest you may want to replace "Fall 2006". "Fall" in this context is not exactly slang or idiom but I think it only has a localized meaning. In any case, it is summer here in Sydney. I'll suggest "December 2006" as a *quick fix*. If this gives you an opportunity to respond with an *architecturally elegant* solution that decouples the reference from the Gregorian Calendar, I'm going to regret ever mentioning this :-). Joe Fernandez Kardinia Software jfernand@kardinia.com www.kardinia.com _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Thu Dec 14 11:03:13 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gut39-00009x-FE; Thu, 14 Dec 2006 11:03:11 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gut37-00009n-TW; Thu, 14 Dec 2006 11:03:09 -0500 Received: from alnrmhc14.comcast.net ([206.18.177.54]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gut35-0003AD-MW; Thu, 14 Dec 2006 11:03:09 -0500 Received: from harrington73653 (c-24-128-104-207.hsd1.nh.comcast.net[24.128.104.207]) by comcast.net (alnrmhc14) with SMTP id <20061214160306b1400ml2i2e>; Thu, 14 Dec 2006 16:03:07 +0000 From: "David Harrington" To: , Date: Thu, 14 Dec 2006 10:59:57 -0500 Message-ID: <146b01c71f98$e89ecdc0$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: Acce/aLJOq0HIRLaT1W9YUubU49q+wAmoOvQ X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 In-Reply-To: <20061213212359.GA4888@boskop.local> X-Spam-Score: 0.0 (/) X-Scan-Signature: 1ac7cc0a4cd376402b85bc1961a86ac2 Cc: Subject: [Isms] RE: [NGO] [Internet-Drafts@ietf.org: I-DACTION:draft-schoenw-snmp-discover-00.txt] X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org > -----Original Message----- > From: Juergen Schoenwaelder [mailto:j.schoenwaelder@iu-bremen.de] > (and I expect > that a sufficient number of SNMP experts are following the ISMS list > anyway). > If they are, I will admit my surprise at their ability to remain absolutely quiet. dbh _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Thu Dec 14 12:36:54 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuuVq-0006Lu-6B; Thu, 14 Dec 2006 12:36:54 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuuVo-0006Lk-TX for isms@ietf.org; Thu, 14 Dec 2006 12:36:52 -0500 Received: from alnrmhc12.comcast.net ([206.18.177.52]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GuuVm-0005Cx-Iz for isms@ietf.org; Thu, 14 Dec 2006 12:36:52 -0500 Received: from harrington73653 (c-24-128-104-207.hsd1.nh.comcast.net[24.128.104.207]) by comcast.net (alnrmhc12) with SMTP id <20061214173648b1200bsg5ge>; Thu, 14 Dec 2006 17:36:48 +0000 From: "David Harrington" To: "'Joe Fernandez'" , Date: Thu, 14 Dec 2006 12:33:30 -0500 Message-ID: <148901c71fa5$ff14b300$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: AccfToOmW0Q71KSgQL+GPtOMz760ewAR2vfg X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 In-Reply-To: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> X-Spam-Score: 0.0 (/) X-Scan-Signature: 3a4bc66230659131057bb68ed51598f8 Cc: Subject: [Isms] RFC3411 architecture and ASIs X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, ********************************************************************** *** This is an unofficial bulletin from the SNMP architectural purity police ********************************************************************** *** ;-) I haven't been following the NGO threads closely over the last two weeks and have not yet reviewed Juergen's draft. So let me only address Joe's question, out of context. > RFC 3411 calls itself an architecture for *describing* SNMP > Management > Frameworks and I take this to mean it should not be > interpreted as the > *required* architecture for *implementing* SNMP Management Frameworks. That is correct. The RFC3411 architecture is not meant to constrain implementations. > RFC 3411 introduces ASIs and says they "are intended to help > clarify the > externally observable behavior of SNMP entities, and are not > intended to > constrain the structure or organization of implementations in > any way." That is correct. The title of RFC3411 very deliberately used "An Architecture" and "for Describing". The primary purpose of the architecture is to develop a modular standard in order to create a consistent terminology for discussion of the conceptual components of an SNMP entity, and the conceptual data flows that occur between the conceptual components to ensure that the right information gets to the pieces that need it. A second purpose of RFC3411 is to make SNMP extensible - to clearly define a minimal set of data-flow dependencies between conceptual subsystems, to make it easier to propose extensions to different portions of the standard within the IETF standards process. Prior to RFC3411, extensions to SNMP pretty much required opening up the whole monolithic standard. It had become clear that different segments of the industry have different needs that could be addressed using extensions to certain portions of the SNMPv3 standard, and that the IETF was unlikely to ever reach consensus on a single specification that met everybody's requirements for different transports, message formats, message security, and data access controls. That trend has continued, and the IETF Management Framework is being opened to using not only different extensions to SNMP, but even non-SNMP protocols are being accepted as part of the IETF management solution. > [...] > As part of this question, I would like to ask David Harrington: With > reference to your recent posting in which you described the > ASIs as highly > unpopular, can you say with whom they are unpopular and why? There are only two groups who really are impacted by the ASIs - implementers and standards developers. Despite the fact we tried to put disclaimers all over the place that the ASIs were about describing minimal conceptual data flows between conceptual subsystems, and not about constraining implementations, and that the ASIs are NOT APIs, the format of the ASI looks like an API, and implementers who tried to implement them as APIs really disliked them. Some implementers disliked the whole conceptualization of subsystems, because it didn't match their implementation, and it became a bit harder to translate the concepts from the standardized modular architecture to their existing implementation architectures. I would have much preferred to use data-flow diagrams (DFDs) in the document to model the flows of data, but we are constrained to 70-column ASCII in IETF documents, and that format does not lend itself to DFD notation. So we chose the current ASI format, which was easily understandable because it looked like a function call. Standards developers disliked it for a different reason. The RFC3411 "descriptive" architecture has become a Full Standard and part of the IETF Standard Management Framework, and it is widely interpreted as the *required* architecture for *designing* IETF-standard SNMP Management Frameworks. To a degree, it stopped being descriptive and became prescriptive (Thanks, Bert for the nice choice of words). But not exactly - the IESG has not mandated RFC3411 as the required architecture for designing IETF-standard SNMP Management Frameworks (unless a WG agrees to it during charter discussions). The "descriptive" architecture standardized the terminology and concepts to discuss design decisions and proposed extensions. If somebody makes a proposal to modify/extend SNMP that uses different terminology and concepts, the members of the IESG are likely to question why the proposal is done using non-standard terminology and concepts. David Harrington dharrington@huawei.com dbharrington@comcast.net ietfdbh@comcast.net _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Thu Dec 14 15:50:15 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuxWq-00089o-Uk; Thu, 14 Dec 2006 15:50:08 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GuxWk-00087v-Ob; Thu, 14 Dec 2006 15:50:02 -0500 Received: from ns1.neustar.com ([2001:503:c779:1a::9c9a:108a]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GuxWk-0008Va-E4; Thu, 14 Dec 2006 15:50:02 -0500 Received: from stiedprstage1.ietf.org (stiedprstage1.va.neustar.com [10.31.47.10]) by ns1.neustar.com (Postfix) with ESMTP id 3B24526E83; Thu, 14 Dec 2006 20:50:02 +0000 (GMT) Received: from ietf by stiedprstage1.ietf.org with local (Exim 4.43) id 1GuxWk-00088v-1A; Thu, 14 Dec 2006 15:50:02 -0500 Content-Type: Multipart/Mixed; Boundary="NextPart" Mime-Version: 1.0 To: i-d-announce@ietf.org From: Internet-Drafts@ietf.org Message-Id: Date: Thu, 14 Dec 2006 15:50:02 -0500 X-Spam-Score: -2.5 (--) X-Scan-Signature: 10ba05e7e8a9aa6adb025f426bef3a30 Cc: isms@ietf.org Subject: [Isms] I-D ACTION:draft-ietf-isms-tmsm-05.txt X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org --NextPart A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Integrated Security Model for SNMP Working Group of the IETF. Title : Transport Subsystem for the Simple Network Management Protocol (SNMP) Author(s) : D. Harrington, J. Schoenwaelder Filename : draft-ietf-isms-tmsm-05.txt Pages : 34 Date : 2006-12-14 This document describes a Transport Subsystem, extending the Simple Network Management Protocol (SNMP) architecture defined in RFC 3411. This document describes a subsystem to contain transport models, comparable to other subsystems in the RFC3411 architecture. As work is being done to expand the transport to include secure transport such as SSH and TLS, using a subsystem will enable consistent design and modularity of such transport models. This document identifies and discusses some key aspects that need to be considered for any transport model for SNMP. 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To use this feature, insert the command "ENCODING mime" before the "FILE" command. To decode the response(s), you will need "munpack" or a MIME-compliant mail reader. Different MIME-compliant mail readers exhibit different behavior, especially when dealing with "multipart" MIME messages (i.e. documents which have been split up into multiple messages), so check your local documentation on how to manipulate these messages. Below is the data which will enable a MIME compliant mail reader implementation to automatically retrieve the ASCII version of the Internet-Draft. --NextPart Content-Type: Multipart/Alternative; Boundary="OtherAccess" --OtherAccess Content-Type: Message/External-body; access-type="mail-server"; server="mailserv@ietf.org" Content-Type: text/plain Content-ID: <2006-12-14124158.I-D@ietf.org> ENCODING mime FILE /internet-drafts/draft-ietf-isms-tmsm-05.txt --OtherAccess Content-Type: Message/External-body; name="draft-ietf-isms-tmsm-05.txt"; site="ftp.ietf.org"; access-type="anon-ftp"; directory="internet-drafts" Content-Type: text/plain Content-ID: <2006-12-14124158.I-D@ietf.org> --OtherAccess-- --NextPart Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms --NextPart-- From isms-bounces@lists.ietf.org Thu Dec 14 22:24:51 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gv3gn-0003Az-8M; Thu, 14 Dec 2006 22:24:49 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gv3gl-0003As-QY for isms@ietf.org; Thu, 14 Dec 2006 22:24:47 -0500 Received: from ipmail01.adl2.internode.on.net ([203.16.214.140]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gv3gj-0005DH-CN for isms@ietf.org; Thu, 14 Dec 2006 22:24:47 -0500 Received: from ppp39-154.lns2.syd6.internode.on.net (HELO wattle.kardinia.com) ([59.167.39.154]) by ipmail01.adl2.internode.on.net with ESMTP; 15 Dec 2006 13:54:39 +1030 X-IronPort-AV: i="4.12,171,1165152600"; d="scan'208"; a="61999267:sNHT34712923" Message-Id: <4.3.2.7.2.20061215141549.0176bcf8@mail.internode.on.net> X-Sender: joe.fernandez@mail.internode.on.net X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Fri, 15 Dec 2006 14:22:40 +1100 To: "David Harrington" , From: Joe Fernandez In-Reply-To: <148901c71fa5$ff14b300$0600a8c0@china.huawei.com> References: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Spam-Score: 0.1 (/) X-Scan-Signature: 9182cfff02fae4f1b6e9349e01d62f32 Cc: Subject: [Isms] Re: RFC3411 architecture and ASIs X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Thanks for the detailed and lucid explanation. At 12:33 PM 14-12-06 -0500, David Harrington wrote: >Hi, > >********************************************************************** >*** >This is an unofficial bulletin from the SNMP architectural purity >police >********************************************************************** >*** > ;-) So is there a Captain Architecture whose responsibility it is to remain vigilant against the threat of QAPDFs (Quick And Possibly Dirty Fixes) and, when he/she sees a proposal for one, to take up his/her cape and Design Patterns handbook and leap into battle for elegance, modularity, and the IETF way? :-) Joe Fernandez Kardinia Software jfernand@kardinia.com www.kardinia.com _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Fri Dec 15 02:44:47 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gv7kG-0001BK-HZ; Fri, 15 Dec 2006 02:44:40 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gv7kF-0001AJ-LH for isms@ietf.org; Fri, 15 Dec 2006 02:44:39 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gv7kC-00069A-25 for isms@ietf.org; Fri, 15 Dec 2006 02:44:39 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id 519D2562C9; Fri, 15 Dec 2006 08:44:33 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 20413-06; Fri, 15 Dec 2006 08:44:29 +0100 (CET) Received: from boskop.local (unknown [10.222.1.3]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id 8A07556095; Fri, 15 Dec 2006 08:44:29 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id 56A2E8FB959; Fri, 15 Dec 2006 08:44:29 +0100 (CET) Date: Fri, 15 Dec 2006 08:44:29 +0100 From: Juergen Schoenwaelder To: Joe Fernandez Subject: Re: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] Message-ID: <20061215074429.GB7487@boskop.local> Mail-Followup-To: Joe Fernandez , isms@ietf.org References: <20061213212359.GA4888@boskop.local> <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> User-Agent: Mutt/1.5.12-2006-07-14 X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: d2b46e3b2dfbff2088e0b72a54104985 Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: j.schoenwaelder@iu-bremen.de List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org On Thu, Dec 14, 2006 at 06:05:09PM +1100, Joe Fernandez wrote: > I have one major question and a few minor ones that are numbered below. > > The question is about registration and Abstract Service Interfaces. > > RFC 3411 calls itself an architecture for *describing* SNMP Management > Frameworks and I take this to mean it should not be interpreted as the > *required* architecture for *implementing* SNMP Management Frameworks. > > The standard specifies what goes on the wire, not what goes in the box, > right? Designers can consent to their modules doing different things in the > privacy of their own nodes. > > RFC 3411 introduces ASIs and says they "are intended to help clarify the > externally observable behavior of SNMP entities, and are not intended to > constrain the structure or organization of implementations in any way." > > The ASIs introduce the concept of applications registering responsibility > for contexts. > > With this background, my question is whether your procedure which seems to > specify that applications have to register in a particular way, is > constraining the implementation in a way that was not originally intended. No. We usually describes things in our architectural framework with the understanding that implementations may choose different ways to achieve the same behavior. In terms of the NET-SNMP code base, I think the actual code change to support the "local" engineID is in the order of roughly 5 lines of code since the registration is kind of hard wired. > It seems to me that the alternative of recognizing a local context constant > does not unduly constrain the implementation to the ASIs. Not sure what you mean here. > As part of this question, I would like to ask David Harrington: With > reference to your recent posting in which you described the ASIs as highly > unpopular, can you say with whom they are unpopular and why? Well, you asked Dave, so I should probably not respond. Personally, I think there are two main reasons why ASIs are sometimes unpopular: (1) People often confuse the ASIs with APIs. The ASIs are conceptual in order to understand the information flow within an SNMP engine and to avoid side effects. Implementations often use a different structure for various reasons and that is just fine. (2) The ASIs are rather precise in defining what data flows where compared to many other IETF protocol standards. This level of precision was actually needed when the ASIs were introduced because the reuse of data items in various parts of what we call an SNMP entity these days did lead to all sorts of problems. Of course, this level of detail makes it also much harder to talk about extensions since (a) you can't simply leave some nasty details to implementors to figure out and (b) the learning curve to enter and follow discussions is rather high. > > Minor questions: > > > 1. > Section 3.1 says "To facilitate discovery, it is assumed that SNMP agents > register their snmpEngineID scalar using a special well known > contextEngineID.". > > I find the wording - "assumed" - odd. > > Don't you need to say something along the lines: This > (standard/specification/whatever) requires an SNMP agent to register its > snmpEngineID using a special well known contextEngineID, which is defined > later in this document and/or the SNMP Framework MIB." or "..an SNMP agent > MUST register....." ? I will fix the wording. > 2. > Section 3.1 says that agent implementations MAY register other objects with > the localEngineID but managers should not count on it. How does the manager > discover which way the implementer has chosen to go (short of trial and > error)? To discover the engineID, the other objects are not needed. I believe managers should simply discover the real engineID and then use the correct engineID. Agent implementations, however, might find it simpler to export all objects in the "local" engineID context. And yes, I do not mind if an application which only needs a single variable during its short lifetime sends a get(snmpEngineID.0, something.0) and is prepared to handle any exceptions or failures by retrying. I believe this is implementation choice. > 3. > I know what your pseudo code is meant to do because we have discussed it > (at some length :-) ) But isn't a new reader going to be baffled by the > code first setting contextEngineID to the localEngineID constant and then > immediately again setting it? There's no ASI here to tell the reader that > the constant is used in the Get. I suggest that you may want to add > comments to this block of pseudo code. I will try to rewrite the pseudo code and add more comments. Perhaps I should introduce a "session" handle which is modified and passed around, as is common in many SNMP APIs I have seen. > 4 > Assorted editorial: > 4.a > Section 1: To retrieve management information using the third version of > the > Simple Network Management Protocol (SNMPv3) [RFC3410], it is > necessary to know the identifier of the remote SNMP protocol engine. > > engineID is also needed for setting. Yes. I will fix this. > 4.b > Section 3: when you say " ..require the snmpEngineID scalar" do you mean > "request" or "acquire", perhaps? Will fix the wording. > 4.c. > Section 3.1 > Some of the references to "agent" may need to be "command responder > application" - ? Yes. I will fix this. > 4.d > Section 4. > Thank you for the generous acknowledgement. It seems curmudgeonly to offer > a correction but since we have been warned of the problems with using slang > and idiom, I'll suggest you may want to replace "Fall 2006". "Fall" in this > context is not exactly slang or idiom but I think it only has a localized > meaning. In any case, it is summer here in Sydney. I'll suggest "December > 2006" as a *quick fix*. If this gives you an opportunity to respond with an > *architecturally elegant* solution that decouples the reference from the > Gregorian Calendar, I'm going to regret ever mentioning this :-). I will fix this as well. Thanks for your feedback. /js -- Juergen Schoenwaelder {International|Jacobs} University Bremen P.O. Box 750 561, 28725 Bremen, Germany _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Fri Dec 15 10:03:10 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GvEaY-0002p1-Fp; Fri, 15 Dec 2006 10:03:06 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GvEaX-0002ow-Bs for isms@ietf.org; Fri, 15 Dec 2006 10:03:05 -0500 Received: from kyoto.netlab.nec.de ([195.37.70.21]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GvEaV-0007vc-1K for isms@ietf.org; Fri, 15 Dec 2006 10:03:05 -0500 Received: from [10.1.1.104] (mito.netlab.nec.de [195.37.70.39]) by kyoto.netlab.nec.de (Postfix) with ESMTP id 24B5C13CF82 for ; Fri, 15 Dec 2006 16:08:02 +0100 (CET) Date: Fri, 15 Dec 2006 16:03:00 +0100 From: Juergen Quittek To: isms@ietf.org Message-ID: X-Mailer: Mulberry/4.0.5 (Mac OS X) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Spam-Score: 0.0 (/) X-Scan-Signature: 798b2e660f1819ae38035ac1d8d5e3ab Cc: Subject: [Isms] working group last call on draft-ietf-isms-tmsm-05 X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Dear all, This is the working group last call on the "Transport Subsystem for the Simple Network Management Protocol (SNMP)" to be found at . The authors and the chairs think that this document is mature enough for last call. Since the holidays are coming, the last call period is not two weeks as usual, but three weeks. Please do review the document and post your comments on this list until January 8, 2007. Please also post to the list if you have read the document and are fine with it. It is very useful to know how many people have read the document. Thanks, Juergen Q. -- Juergen Quittek quittek@netlab.nec.de Tel: +49 6221 4342-115 NEC Europe Ltd., Network Laboratories Fax: +49 6221 4342-155 Kurfuersten-Anlage 36, 69115 Heidelberg, Germany http://www.netlab.nec.de _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 20 06:31:10 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GwzfC-0008PP-AI; Wed, 20 Dec 2006 06:31:10 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GwzfB-0008PF-D4 for isms@ietf.org; Wed, 20 Dec 2006 06:31:09 -0500 Received: from ipmail02.adl2.internode.on.net ([203.16.214.141]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gwzf6-0005Nn-IA for isms@ietf.org; Wed, 20 Dec 2006 06:31:09 -0500 Received: from ppp2-22.lns1.syd7.internode.on.net (HELO wattle.kardinia.com) ([59.167.2.22]) by ipmail02.adl2.internode.on.net with ESMTP; 20 Dec 2006 22:00:56 +1030 X-IronPort-AV: i="4.12,192,1165152600"; d="scan'208"; a="62875449:sNHT49022260" Message-Id: <4.3.2.7.2.20061220213300.024aa4b0@mail.internode.on.net> X-Sender: joe.fernandez@mail.internode.on.net X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Wed, 20 Dec 2006 22:28:47 +1100 To: j.schoenwaelder@iu-bremen.de From: Joe Fernandez Subject: Re: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] In-Reply-To: <20061215074429.GB7487@boskop.local> References: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> <20061213212359.GA4888@boskop.local> <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Spam-Score: 0.1 (/) X-Scan-Signature: 10ba05e7e8a9aa6adb025f426bef3a30 Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org At 08:44 AM 15-12-06 +0100, Juergen Schoenwaelder wrote: [..] > > The ASIs introduce the concept of applications registering responsibility > > for contexts. > > > > With this background, my question is whether your procedure which seems to > > specify that applications have to register in a particular way, is > > constraining the implementation in a way that was not originally intended. > >No. We usually describes things in our architectural framework with >the understanding that implementations may choose different ways to >achieve the same behavior. In terms of the NET-SNMP code base, I think >the actual code change to support the "local" engineID is in the order >of roughly 5 lines of code since the registration is kind of hard >wired. > > > It seems to me that the alternative of recognizing a local context > constant > > does not unduly constrain the implementation to the ASIs. > >Not sure what you mean here. I mean that it seems to me possible to specify support for a local context by recognition of a local contextEngineID constant without constraining the implementation to take section 4 of RFC 3411 as prescriptive. If you start with the ASIs in mind as your model, then you tend to be driven by thinking along the lines of an application code module registering responsibility for contextEngineIDs. But the standard is purely to achieve interoperability, right, so its about bits on the wire not code in the node. In practice in most cases there will not be a proxy and in many cases a manager will be talking to a single agent that has a single contextEngineID. So the manager should have a simple way to tell the agent to use its default contextEngineID and gain access to all objects in the named context. [..] >(2) The ASIs are rather precise in defining what data flows where > compared to many other IETF protocol standards. This level of > precision was actually needed when the ASIs were introduced > because the reuse of data items in various parts of what we call > an SNMP entity these days did lead to all sorts of problems. Of > course, this level of detail makes it also much harder to talk > about extensions since (a) you can't simply leave some nasty > details to implementors to figure out ...perhaps you can, but I'll agree that it is much kinder to provide guidance in the form of a possible implementation scenario. The question then is when this guidance goes from being descriptive to being prescriptive. Your proposal explicitly leaves open the possibilities that agents may make either just snmpEngineID accessible under this contextEngineID or additional objects, which could be "all" objects. How about defining two well known constants, one for the single object case, the other for the all object case? Then if the agent is known to have implemented the latter, the manager knows it can access any object in a single operation by using the second constant. If you do not see any objections to this alternative I can draft the text for it. [..] > > and idiom, I'll suggest you may want to replace "Fall 2006". "Fall" in > this > > context is not exactly slang or idiom but I think it only has a localized > > meaning. In any case, it is summer here in Sydney. I'll suggest "December > > 2006" as a *quick fix*. If this gives you an opportunity to respond > with an > > *architecturally elegant* solution that decouples the reference from the > > Gregorian Calendar, I'm going to regret ever mentioning this :-). > >I will fix this as well. I hope it was clear that this last comment was meant as a joke and that it did not cause any offence. Email is a deadly medium where attempts at humour sometimes go off the rails.... Joe Fernandez Kardinia Software jfernand@kardinia.com www.kardinia.com _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 20 18:20:42 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GxAjk-0005Xg-RA; Wed, 20 Dec 2006 18:20:36 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GxAjj-0005UK-Dq for isms@ietf.org; Wed, 20 Dec 2006 18:20:35 -0500 Received: from hermes.iu-bremen.de ([212.201.44.23]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GxAjh-0004sD-Vt for isms@ietf.org; Wed, 20 Dec 2006 18:20:35 -0500 Received: from localhost (demetrius.iu-bremen.de [212.201.44.32]) by hermes.iu-bremen.de (Postfix) with ESMTP id 42A8855F83; Thu, 21 Dec 2006 00:20:33 +0100 (CET) Received: from hermes.iu-bremen.de ([212.201.44.23]) by localhost (demetrius.iu-bremen.de [212.201.44.32]) (amavisd-new, port 10024) with ESMTP id 08428-10; Thu, 21 Dec 2006 00:20:30 +0100 (CET) Received: from boskop.local (unknown [10.222.1.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by hermes.iu-bremen.de (Postfix) with ESMTP id EC5E055DA0; Thu, 21 Dec 2006 00:20:29 +0100 (CET) Received: by boskop.local (Postfix, from userid 501) id 3354D902B2D; Thu, 21 Dec 2006 00:20:28 +0100 (CET) Date: Thu, 21 Dec 2006 00:20:27 +0100 From: Juergen Schoenwaelder To: Joe Fernandez Subject: Re: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] Message-ID: <20061220232027.GC1497@boskop.local> Mail-Followup-To: Joe Fernandez , isms@ietf.org References: <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> <20061213212359.GA4888@boskop.local> <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> <4.3.2.7.2.20061220213300.024aa4b0@mail.internode.on.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4.3.2.7.2.20061220213300.024aa4b0@mail.internode.on.net> User-Agent: Mutt/1.5.10i X-Virus-Scanned: amavisd-new 2.3.3 (20050822) at iu-bremen.de X-Spam-Score: 0.0 (/) X-Scan-Signature: a7d6aff76b15f3f56fcb94490e1052e4 Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: j.schoenwaelder@iu-bremen.de List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org On Wed, Dec 20, 2006 at 10:28:47PM +1100, Joe Fernandez wrote: > If you start with the ASIs in mind as your model, then you tend to be > driven by thinking along the lines of an application code module > registering responsibility for contextEngineIDs. But the standard is purely > to achieve interoperability, right, so its about bits on the wire not code > in the node. > > In practice in most cases there will not be a proxy and in many cases a > manager will be talking to a single agent that has a single > contextEngineID. So the manager should have a simple way to tell the agent > to use its default contextEngineID and gain access to all objects in the > named context. Or the manager simply uses the "real" contextEngineID... > Your proposal explicitly leaves open the possibilities that agents may make > either just snmpEngineID accessible under this contextEngineID or > additional objects, which could be "all" objects. > > How about defining two well known constants, one for the single object > case, the other for the all object case? Then if the agent is known to have > implemented the latter, the manager knows it can access any object in a > single operation by using the second constant. > > If you do not see any objections to this alternative I can draft the text > for it. I strongly dislike adding a second constant to avoid finding agreement on the scope of a single constant. You did not really say why you want to require "all" objects under the "local" contextEngineID. Is it because you want to safe a round-trip time because you can get away without doing a contextEngineID discovery? Are there other reasons? And yes, I would love to hear more opinions. Anyone out there following this discussion? /js -- Juergen Schoenwaelder {International|Jacobs} University Bremen P.O. Box 750 561, 28725 Bremen, Germany _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Thu Dec 21 07:19:40 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GxMtd-0008LQ-Cw; Thu, 21 Dec 2006 07:19:37 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GxMtb-0008LL-RL for isms@ietf.org; Thu, 21 Dec 2006 07:19:35 -0500 Received: from ipmail02.adl2.internode.on.net ([203.16.214.141]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GxMta-0005g9-5M for isms@ietf.org; Thu, 21 Dec 2006 07:19:35 -0500 Received: from ppp33-178.lns1.syd6.internode.on.net (HELO wattle.kardinia.com) ([59.167.33.178]) by ipmail02.adl2.internode.on.net with ESMTP; 21 Dec 2006 22:49:28 +1030 X-IronPort-AV: i="4.12,199,1165152600"; d="scan'208"; a="63326871:sNHT37583756" Message-Id: <4.3.2.7.2.20061221224108.01789b80@mail.internode.on.net> X-Sender: joe.fernandez@mail.internode.on.net X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Thu, 21 Dec 2006 23:12:37 +1100 To: j.schoenwaelder@iu-bremen.de From: Joe Fernandez Subject: Re: [Isms] [Internet-Drafts@ietf.org: I-D ACTION:draft-schoenw-snmp-discover-00.txt] In-Reply-To: <20061220232027.GC1497@boskop.local> References: <4.3.2.7.2.20061220213300.024aa4b0@mail.internode.on.net> <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> <20061213212359.GA4888@boskop.local> <4.3.2.7.2.20061214175628.01764d10@mail.internode.on.net> <4.3.2.7.2.20061220213300.024aa4b0@mail.internode.on.net> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed X-Spam-Score: 0.1 (/) X-Scan-Signature: 34d35111647d654d033d58d318c0d21a Cc: isms@ietf.org X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, At 12:20 AM 21-12-06 +0100, Juergen Schoenwaelder wrote: > > In practice in most cases there will not be a proxy and in many cases a > > manager will be talking to a single agent that has a single > > contextEngineID. So the manager should have a simple way to tell the agent > > to use its default contextEngineID and gain access to all objects in the > > named context. > >Or the manager simply uses the "real" contextEngineID... But in the situation we are discussing the manager does not know what the real contextEngineID is. That's why you created this Internet-Draft on EngineID Discovery, right? So the two options we are discussing are: a) the manager says "tell me what your engineID is so I can echo it back to you and get you to use it" or b)the manager says "use your own engineID, whatever it may be " Option a) seems unnecessarily artificial and roundabout to me. > > Your proposal explicitly leaves open the possibilities that agents may > make > > either just snmpEngineID accessible under this contextEngineID or > > additional objects, which could be "all" objects. > > > > How about defining two well known constants, one for the single object > > case, the other for the all object case? Then if the agent is known to > have > > implemented the latter, the manager knows it can access any object in a > > single operation by using the second constant. > > > > If you do not see any objections to this alternative I can draft the text > > for it. > >I strongly dislike adding a second constant to avoid finding agreement >on the scope of a single constant. But doesn't your proposal avoid finding agreement on the scope of your single constant, anyway? See my first para of my three paras above......the one that starts "Your proposal explicitly.." >You did not really say why you want >to require "all" objects under the "local" contextEngineID. Is it >because you want to safe a round-trip time because you can get away >without doing a contextEngineID discovery? Are there other reasons? There's a design principle that says something along the lines that a good design should be no more complex than it needs to be. It is usually stated in a more elegant and simple way than that but I forget what the usual statement is. I think I stated that this was the basis of my objection, in the earlier discussion on the NGO mailing list. I still think that it is because I am not approaching the solution from the ASI point of view that I think a simple clean solution is to have the manager send a contextEngineID value that means "this" engine (and that is, of course, not an original contribution from me.) >And yes, I would love to hear more opinions. Anyone out there >following this discussion? > I am just wondering if I can call this the "You talkin' to me?" problem without incurring the wrath of David Harrington. Before he sends me to the sin bin, I want to say that this quote has an entry in Wikipedia that anyone on this list can look up, if the quote does not mean anything to them. The manager engages in an interaction with the agent but does not know the agent's engineID So the agent says "You talkin' to me?" . We both agree that even though this is not a proxy situation, we do not want the agent to go "Well I'm the only one here", but we are still having a minor disagreement on what the agent's behaviour should be. So yes, other views would be good. Joe Fernandez Kardinia Software jfernand@kardinia.com www.kardinia.com _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms From isms-bounces@lists.ietf.org Wed Dec 27 15:09:32 2006 Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gzf5V-0005bK-1k; Wed, 27 Dec 2006 15:09:21 -0500 Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1Gzf5T-0005bF-P8 for isms@ietf.org; Wed, 27 Dec 2006 15:09:19 -0500 Received: from alnrmhc13.comcast.net ([204.127.225.93]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1Gzf5S-0000je-IC for isms@ietf.org; Wed, 27 Dec 2006 15:09:19 -0500 Received: from harrington73653 (ip67-155-163-250.z163-155-67.customer.algx.net[67.155.163.250]) by comcast.net (alnrmhc13) with SMTP id <20061227200917b1300pht49e>; Wed, 27 Dec 2006 20:09:17 +0000 From: "David Harrington" To: , Date: Wed, 27 Dec 2006 15:06:03 -0500 Message-ID: <197a01c729f2$724ad600$0600a8c0@china.huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook 11 Thread-Index: Accl6KnohSZvVJIwT5WlDT4y0/sDsQ== X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Spam-Score: 0.0 (/) X-Scan-Signature: 7655788c23eb79e336f5f8ba8bce7906 Cc: Subject: [Isms] discovery X-BeenThere: isms@lists.ietf.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Mailing list for the ISMS working group List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: isms-bounces@lists.ietf.org Hi, I recommend standardizing the discovery mechanisms to include three pieces of data - contextengineID, sysDescriptor, and sysObjectID. Those three items identify the SNMP entity. Naming the variables that can be returned by a compliant implementation of this mechanism allows us to discuss the security considerations of the data revealed. Leaving it to the implementation to allow any data in the request/response makes it pretty much impossble to describe the security implications of the discovery mechanism. It could be argued that additional system objects could be included in the discovery, and we can discuss the security implications of including those in the request. David Harrington dharrington@huawei.com dbharrington@comcast.net ietfdbh@comcast.net _______________________________________________ Isms mailing list Isms@lists.ietf.org https://www1.ietf.org/mailman/listinfo/isms