RE: [Syslog] Discuss - UDP Checksum

[Chris Lonvick]

Hi,

I don't think that addresses the IESG concerns as well as Juergen's 
proposal.

I'd like to wrap this up.  I don't think that there's any disagreement 
that we need something like this.  Would anyone with any other thoughts 
please send them in.  David and I will determine consensus tomorrow.  :-)

Thanks,
Chris

On Tue, 10 Jul 2007, Anton Okmyanskiy (aokmians) wrote:

I agree with Juergen and Rainer that we could use less specification
here since it is a different layer.  How about we replace both
paragraphs with this:

"Syslog senders are RECOMMENDED to use UDP checksums when sending
messages over IPv4. Proper UDP checksum insertion and verification is
already required by IPv6 RFC 1883."

Let's be silent on what the receiver has to do since it may not have any
control.  I think if we put something like "Syslog receivers MAY accept
syslog message with invalid or zero checksums", it would directly
contradict IPv6 RFC, which says:

"IPv6 receivers must discard UDP packets containing a zero checksum, and
should log the error."

Anton.

-----Original Message-----
From: Juergen Schoenwaelder
[EMAIL PROTECTED]
Sent: Thursday, July 05, 2007 4:16 PM
To: Chris Lonvick (clonvick)
Cc: [EMAIL PROTECTED]
Subject: Re: [Syslog] Discuss - UDP Checksum

On Thu, Jul 05, 2007 at 02:14:06PM -0700, Chris Lonvick wrote:

How about the following:

   syslog senders MUST NOT disable UDP checksums.  syslog
senders SHOULD
   use UDP checksums when sending messages over IPv4.
syslog senders MUST
   use UDP checksums when sending messages over IPv6.

The last sentence is a bit like requiring that the IPv6
implementation your code happens to run on MUST be correct
(and I have no clue how to turn this requirement into syslog code).

   syslog receivers should be lenient in what they receive.  IPv4
   receivers SHOULD check the UDP checksums.  They SHOULD accept a
   syslog message with a zero checksum.  They MAY discard messages
   with invalid checksums, or they MAY accept them and
attempt to process
   them.  IPv6 receivers MUST check the UDP checksums and
MUST discard UDP
   packets containing a zero checksum.

I am not sure the MAY discard or MAY accept sentence is needed.

My proposal would be:

    syslog senders MUST NOT disable UDP checksums.  IPv4 syslog
    senders SHOULD use UDP checksums when sending messages. Note that
    RFC 2460 [RFC2460] mandates the use of UDP checksums when sending
    UDP datagrams over IPv6.

    syslog receivers MUST NOT disable UDP checksum checks. IPv4 syslog
    receivers SHOULD check UDP checksums and they SHOULD accept a
    syslog message with a zero checksum. Note that RFC 2460 [RFC2460]
    mandates the use of checksums for UDP over IPv6.

By simply refering to the IPv6 requirement for UDP checksums,
we avoid making this also a syslog requirement. I think we
should not use MUST language for something that can only be
implemented correctly below the syslog software layer.

[Enough hair splitting for today. ;-]

/js

--
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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