openssh unix dev - Feb 2011 - Code review request: Drop obsolete RFC-791 markings for QoS markings

Here's the bug and proposed patch.  It's pretty trivial.

https://bugzilla.mindrot.org/show_bug.cgi?id=1856


Quoting RFC-2474:

    A replacement header field, called the DS field, is defined, which is
intended to supersede the existing definitions of the IPv4 TOS octet [RFC791]
and the IPv6 Traffic Class octet [IPv6]. [...] The structure of the DS field
shown above is incompatible with the existing definition of the IPv4 TOS octet
in [RFC791].

and:

    No attempt is made to maintain backwards compatibility with the
"DTR" or TOS bits of the IPv4 TOS octet, as defined in [RFC791].

Also note that the patch that was originally proposed (but not accepted as-is)
for bug 1733 attempted to disallow user setting of the QoS bits, also in
accordance with RFC-2474:

    Correct operational procedure SHOULD follow [RFC791], which states: "If
the actual use of these precedence designations is of concern to a particular
network, it is the responsibility of that network to control the access to, and
use of, those precedence designations."

According to www.rfc-editor.org, RFC 791 is not obsolete and is still a
standard, although it is updated by RFC 1349. Whereas RFC 2474 is only a
proposed standard.

Is that correct?

On Fri, Feb 18, 2011 at 16:03:44 -0600, Philip Prindeville
wrote:
> Here's the bug and proposed patch.  It's pretty trivial.
> 
> https://bugzilla.mindrot.org/show_bug.cgi?id=1856
> 
> 
> Quoting RFC-2474:
> 
>     A replacement header field, called the DS field, is defined, which is
intended to supersede the existing definitions of the IPv4 TOS octet [RFC791]
and the IPv6 Traffic Class octet [IPv6]. [...] The structure of the DS field
shown above is incompatible with the existing definition of the IPv4 TOS octet
in [RFC791].
> 
> and:
> 
>     No attempt is made to maintain backwards compatibility with the
"DTR" or TOS bits of the IPv4 TOS octet, as defined in [RFC791].
> 
> Also note that the patch that was originally proposed (but not accepted
as-is) for bug 1733 attempted to disallow user setting of the QoS bits, also in
accordance with RFC-2474:
> 
>     Correct operational procedure SHOULD follow [RFC791], which states:
"If the actual use of these precedence designations is of concern to a
particular network, it is the responsibility of that network to control the
access to, and use of, those precedence designations."
> 
> 
> _______________________________________________
> openssh-unix-dev mailing list
> openssh-unix-dev at mindrot.org
> https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
-- 
Iain Morgan