Re: "unclean" ?bug? with dell dns

Re: "unclean" ?bug? with dell dns

[Rainer Ellinger]

Guillaume Morin wrote:
> >  When i "dig www.euro.dell.com", i get in syslog :
> I'd say that unclean matches the packet because of a checksum
> mismatch. There must be a buggy router between you and the server.

I ran into the same problem and can also confirm that this is a problem 
with dell's nameserver or a system on dell's side. Further 
investigation with ethereal showed that matching pakets had their udp 
crc set to 0x0000. My questions are: 

Should this condition really considered harmful and matched by unclean?
Why is there no corresponding log message from the unclean module?

-- 
rainer@ellinger.de

Re: "unclean" ?bug? with dell dns

[Guillaume Morin]

Hi Rainer,

Dans un message du 09 sep à 20:27, Rainer Ellinger écrivait :
> investigation with ethereal showed that matching pakets had their udp 
> crc set to 0x0000. My questions are: 
> 
> Should this condition really considered harmful and matched by unclean?

No, that's a bug. I'll submit a patch for that.

> Why is there no corresponding log message from the unclean module?

The consensus is that for a simple checksum error a log message is not
needed. 

Regards,

-- 
Guillaume Morin <guillaume@morinfr.org>

        Justice is lost, Justice is raped, Justice is done. (Metallica)

Re: "unclean" ?bug? with dell dns

[Jozsef Kadlecsik]

On Mon, 9 Sep 2002, Rainer Ellinger wrote:

> Guillaume Morin wrote:
> > >  When i "dig www.euro.dell.com", i get in syslog :
> > I'd say that unclean matches the packet because of a checksum
> > mismatch. There must be a buggy router between you and the server.
>
> I ran into the same problem and can also confirm that this is a problem
> with dell's nameserver or a system on dell's side. Further
> investigation with ethereal showed that matching pakets had their udp
> crc set to 0x0000. My questions are:
>
> Should this condition really considered harmful and matched by unclean?

I don't think so. UDP checksumming is not mandatory, but the unclean
module accepts only packets with valid checksums.

> Why is there no corresponding log message from the unclean module?

Because the unclean module does not log packets with invalid checksums.

Regards,
Jozsef
-
E-mail  : kadlec@blackhole.kfki.hu, kadlec@sunserv.kfki.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : KFKI Research Institute for Particle and Nuclear Physics
          H-1525 Budapest 114, POB. 49, Hungary

Re: "unclean" ?bug? with dell dns

[Jozsef Kadlecsik]

On Mon, 9 Sep 2002, Rainer Ellinger wrote:

> Guillaume Morin wrote:
> > >  When i "dig www.euro.dell.com", i get in syslog :
> > I'd say that unclean matches the packet because of a checksum
> > mismatch. There must be a buggy router between you and the server.
>
> I ran into the same problem and can also confirm that this is a problem
> with dell's nameserver or a system on dell's side. Further
> investigation with ethereal showed that matching pakets had their udp
> crc set to 0x0000. My questions are:
>
> Should this condition really considered harmful and matched by unclean?

I don't think so. UDP checksumming is not mandatory, but the unclean
module accepts only packets with valid checksums.

> Why is there no corresponding log message from the unclean module?

Because the unclean module does not log packets with invalid checksums.

Regards,
Jozsef
-
E-mail  : kadlec@blackhole.kfki.hu, kadlec@sunserv.kfki.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : KFKI Research Institute for Particle and Nuclear Physics
          H-1525 Budapest 114, POB. 49, Hungary