Re: [Tls-reg-review] Request to Register Value in TLS ALPN Registry

[Yoav Nir <[e-mail]>]

On 9 Aug 2019, at 23:45, Thakar, Eeshan <thakar=[e-mail]> wrote:

> Type of Assignment:
> Registration of “mqtt” token
>  
> Registry:
> Application Layer Protocol Negotiation (ALPN) Protocol ID
>  
> Description:
> The mqtt protocol has the protocol version written into the first message on a connection. The mqtt server implementations typically understand the protocol version based on the fixed header on the first message (connect).
>  
> Adding this protocol id to the registry will help the community since clients wanting to request mqtt as the protocol would have an appropriate specification reference to use.
>  
> Additional Info:
> [1] MQTT 3.1 Specification: http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html <http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/mqtt-v3r1.html>
> [2] MQTT 3.1.1 Specification: http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/csprd02/mqtt-v3.1.1-csprd02.html <http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/csprd02/mqtt-v3.1.1-csprd02.html>
> [3] MQTT 5.0 Specification: http://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html <http://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html>
>  

Hi, Eeshan.

I’ve looked through the linked specifications, especially the third one because it says it replaces the others.

It says that TCP port 8883 is registered with IANA for MQTT over TLS, and the IANA registry confirms it.  If you have your own port, why do you need ALPN?

ALPN is used to negotiate a particular service (such as HTTP) over a single port, typically 443.  

So if you were using a server listening on port 443 and serving both MQTT and HTTP/2 you would need that to distinguish clients that need MQTT from web browsers that need HTTP/2.

The linked document does not make any mention of such a server.  Is this described elsewhere?

Thanks

Yoav