Re: ICMP in 2.2.9 (was 3c575)

jakob@ostenfeld.dk
Fri, 11 Jun 1999 05:00:43 +0200


On Fri, Jun 11, 1999 at 03:26:56AM +0100, Alan Cox wrote:
> > Can anyone confirm, that it is not possible to ping machines running
> > the 2.2.9 kernel with ping packets of size 1475 ?
>
> Yes. Just fine. You probably have a buggy ping binary.

But it's a buggy ping binary on three different releases of redhat
on four different kernels then.

I do ping -s 1475 some.host.somewhere and get no replies.

This is getting weirder by the minute... Perhaps I should get some
sleep soon...

Host 1 (2.2.7, RH5.9, 3com905)
Host 2 (2.2.3, RH5.2, Tulip)
Host 3 (2.0.36, RH5.1, Tulip)
Host 4 (2.2.9, RH6.0, Tulip)

1 2 3 4 (destination)
---------------------
1| N N N
2| Y Y Y
3| Y Y Y
4| N N N
(source)

Yikes. The pattern as I see it is, ping with glibc2.1 cannot
send _good_ ICMP echo requests.

The really funny thing is, that where you see a `N', eg. when host
1 pings host 3, the echo request packets actually reaches host 3,
but host 3 never sends a reply. (Seen with tcpdump on host 3)
I guess the kernel discards the requests for some reason (??)

Unfortunately I only have RedHat boxes around here, so I can't test
whether it's just RedHat's ping in 5.9 and 6.0 that's screwed, or
it's the glibc. But ok, this is not a kernel issue. Darn, so close :)

Regards,

................................................................
: jakob@ostenfeld.dtu.dk : And I see the elder races, :
:.........................: putrid forms of man :
: Jakob Østergaard : See him rise and claim the earth, :
: OZ9ABN : his downfall is at hand. :
:.........................:............{Konkhra}...............:

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