RE: [Syslog] Discuss - UDP Checksum

["Rainer Gerhards" <rgerhards at hq.adiscon.com>]

[Strictly speaking as an implementor, not as a draft editor]

I second Juergen's point of view.

I go even further. When receiving, I take great care not to loose any
message. Under stress conditions (e.g. low system memory), I accept lage
deformations of the message. Checksums are my least concern and I
wouldn't discard a message "just" because the checksum is invalid. I
will defintely ignore any such MUST in a RFC, at least by default. I
may, however, flag this message as being in error (which possibly means
it ends up in a different bin). The reasoning behind all this is that a
vital message might be lost forever and it is better to receive it in
some degraded state. At least this is what my *actual* users are
requesting.

Rainer

> -----Original Message-----
> From: Juergen Schoenwaelder 
> [mailto:j.schoenwaelder at jacobs-university.de] 
> Sent: Thursday, July 05, 2007 9:24 PM
> To: Chris Lonvick
> Cc: syslog at ietf.org
> Subject: Re: [Syslog] Discuss - UDP Checksum
> 
> On Thu, Jul 05, 2007 at 11:51:13AM -0700, Chris Lonvick wrote:
> 
> > Which brings us back to our original question.  Is the 
> proposed language 
> > below what the WG wants?
> 
> As an implementor, I have a problem with the statement
> 
>   syslog senders MUST use UDP checksums when sending messages 
> over IPv4
> 
> since on several platforms, I simply can't ensure this when I write a
> portable SYSLOG implementation. So I can either claim my code to be
> RFC compliant while in a real deployment it might not behave
> conforming to the RFC (depending on the kernel settings for example),
> or I tell the truth that I can never guarantee compliant behaviour of
> my implementation.
> 
> So if we need to have language at all, what about
> 
>   syslog senders MUST NOT disable UDP checksums
> 
> This is something I can implement much more easily since the default
> seems to be enabled on those platforms I am familiar with. ;-) 
> 
> Or alternatively go back to SHOULD
> 
>   syslog senders SHOULD use UDP checksums when sending 
> messages over IPv4
> 
> with the likely non-obvious interpretation that you should enable /
> not disable checksums in your code but if the kernel bites you, you
> are still fine.
> 
> My point is that if we put out requirements for implementations, lets
> do this in a way that a coder can reasonably implement them.
> 
> /js
> 
> [No, I am not implementing SYSLOG right now - but I am familiar with
>  other protocols running over UDP and hence this got my attention.]
> 
> -- 
> Juergen Schoenwaelder           Jacobs University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1, 28759 Bremen, Germany
> Fax:   +49 421 200 3103         <http://www.jacobs-university.de/>
> 
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