Re: [Netconf] xml start directive with ssh

[Phil Shafer <phil at juniper.net>]

David Reid writes:
>>From rfc4742 page 3:
>
>   Once the SSH session has been established, the user (or application)
>   will invoke NETCONF as an SSH subsystem called "netconf".  Subsystem
>   support is a feature of SSH version 2 (SSHv2) and is not included in
>   SSHv1.  Running NETCONF as an SSH subsystem avoids the need for the
>   script to recognize shell prompts or skip over extraneous
>   information, such as a system message that is sent at shell start-up.
>   However, even when a subsystem is used, some extraneous messages may
>   be printed by the user's start-up scripts.  Implementations MUST skip
>   over these messages by searching for an 'xml' start directive, which
>   MUST be followed by a <hello> element in the 'NETCONF' namespace.

IMHO this is not right.  An SSH subsystem won't run "user's start-up
scripts", so the skipping issue is moot.  Also "'xml' start directive"
should be "XML Declaration", but that's minor.

>Both the netconf client and server MUST send an xml start directive before
>the <hello> message and MAY send an xml start directive before any other
>message when running over SSH.

Since hello and other messages are individual XML documents, they
MAY being with an XML declaration.

>Anything sent by either the client or server before the xml start directive
>MUST be ignored when running over SSH.

This is what it says, but I don't see this as real world.

>When not running over SSH, any extraneous data results in a parse error.

This RFC can't say anything about other transports.

Thanks,
 Phil