Messages in this thread | | | Date | Sat, 12 Jun 1999 15:48:59 -0400 | From | Dennis <> | Subject | Re: ICMP in 2.2.9 (was 3c575) |
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At 05:00 AM 6/11/99 +0200, jakob@ostenfeld.dk wrote: >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 :)
do a netstat -s on both the sending and receiving boxes to see what the error counters say. A 1475 byte packet happends to be exactly 1514 bytes (the mtu max, typically) so you may have an mtu problem
DB
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