Re: [OPSAWG] Declaring something to be a controller in MUD

Qin Wu <> Tue, 02 July 2019 01:23 UTC

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From: Qin Wu <>
To: Eliot Lear <>
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Thread-Topic: [OPSAWG] Declaring something to be a controller in MUD
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Date: Tue, 2 Jul 2019 01:22:54 +0000
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Subject: Re: [OPSAWG] Declaring something to be a controller in MUD
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Hi, Eliot:
Sorry for late, see my reply inline below.

发件人: Eliot Lear []
发送时间: 2019年7月1日 16:49
收件人: Qin Wu <>
主题: Re: [OPSAWG] Declaring something to be a controller in MUD

On 1 Jul 2019, at 10:23, Qin Wu <<>> wrote:

发件人: Eliot Lear []
发送时间: 2019年7月1日 15:52
收件人: Qin Wu <<>>
主题: Re: [OPSAWG] Declaring something to be a controller in MUD

On 1 Jul 2019, at 09:20, Qin Wu <<>> wrote:

发件人: OPSAWG [] 代表 Eliot Lear
发送时间: 2019年6月24日 17:48
主题: [OPSAWG] Declaring something to be a controller in MUD

Hi everyone,

A few of us are just trying to put out an initial draft that addresses one gap in MUD (there are several).  In a MUD file one can say that one wants to access a controller in two ways: either "my-controller” meaning a controller that services devices of a particular MUD URL or a “controller” class that services devices based on a particular class name of controller.

In either case, right now the administrator has to manually know and populate information, to say - some device is a controller, either for MUD URL or a class  That can be laborious.  To assist, we are examining ways to have a controller declare itself as a candidate controller.

[Qin]: Since MUD in RFC8520 has already specify DNS extension and DHCP extension, why not configure MUD manager with controller’s declaration? So the RESTFUL interface can be defined between NMS and controller, if my understanding is correct.
I believe this is network initiated solution, you might have client initiated solution, but probably more complicated than network initiated solution.

Can you say a few more words?  I’m not sure I’m quite following you.
[Qin]: What I am suggesting is NMS preconfigures the MUD manager with controller’s declaration information, during DHCP process or DNS process, the controller’s declaration can be returned
To the router or switch between the thing and MUD manager or return to the thing, the router or the thing can access controller through controller delclartion.

If the MUD manager also needs to be advertised to the thing, DHCP Discovery or DNS process can be leveraged. In this case, NMS needs to preconfigure DHCP server with MUD manager information.

I apologize, but I’m not quite following.  Let’s step through what I’m trying to solve, and then let’s step through your flow.

Device sends a MUD URL X that points to a MUD file that says to permit ip access to my-controller.

Now- how do we determine who “my-controller” for MUD URL X is?

Ways to do that:

  *   Ask the administrator (pre-configuration)
  *   Provide the administrator hints

     *   Controller says who it can control (by MUD URLs, etc) or
     *   Device says which controllers (by MUD URL) are good candidates

  *   Other
[Qin]: My simply proposal is to assume NMS knows who “my-controller”for MUD URL X is in advance or NMS has already select a list of my-controller devices corresponding to MUD URL for the thing. So NMS can preconfigure DHCP server with my-controller identity.
During DHCP process, it can return MUD URL together with my-controller identity.
This is centralized solution comparing with your second option: provide administrator hints.
What you propose in the second option is distributed solution, allow controller and device to discover each other.

If it’s the controller, then we can do a RESTful interface.  If it’s the device, we already have a communication path.

Nothing stops us from doing both.
[Qin]: I am not sure you need to do both, either controller device tell the thing I am controller or device discover one device can server as controller.
So now insert your approach.  What steps would you take?



 That at least provides a hint to the administrator that this particular device is capable of serving in a particular role.

To make that declaration, the device must-

  *   Form the declaration;
  *   Find the MUD manager; and
  *   Send it.

Forming the declaration is easy: we can make this a YANG grouping and then place it in various spots.

Finding the MUD manager depends on one question:

  *   Was the device built to be a controller or is it a general purpose device that has an app that is intended to be a controller?

If the device was built to be a controller, we can simply cram the declaration into that devices own MUD file as an extension.  If the device is a general purpose computer, things get a bit more interesting.  In this case we have two choices:

  *   Either create a MUD file that points somewhere internally - this doesn’t seem very plug and play.
  *   Make the declaration directly to the MUD manager.

I’m going to focus on the latter for the moment.  It is easy enough to create a RESTful interface for this purpose, but it requires a mechanism to discovered the MUD manager, which up until now has been an internal part of the network infrastructure.

Let me call this out plainly: letting the app itself directly call the MUD manager requires that the MUD manager itself become exposed to the user infrastructure, which is a change.

One possibility to address this is to incorporate the new RESTful endpoint into an ANIMA BRSKI join registrar, which may already be exposed.  But that requires that ANIMA BRSKI be in play, which it may not.

My thinking is that we do this work in two stages.  First handle the easy case, which is the MUD file extension, and then figure out how to do the app version of this.