1. Strange network problems - pings to host are fine, pings from host fail
Sorry for the long post - I've tried to outline the symptoms of my
problem, and what I've tried to fix it.
I'm having some networking problems with a PC running an old version of
Red Hat (kernel 2.2). The PC came with a machine we have bought
second-hand - as far as I know, everything was working before the
machine was moved to our company.
To keep things simple, we have the Red Hat machine connected to a
Windows XP machine that came with it, with only a simple switch in
between. Each machine is set up with a fixed IP address on the same
From the XP machine, I can ping the Red Hat machine reliably and
quickly. From the Red Hat machine, pings to the XP machine /generally/
fail - typically there are about 80%-90% failures. Those pings that
don't fail, are fast (reply time about 1 ms). On the XP machine, it's
easy to see the packet counters showing packets in and replies out. On
the Red Hat machine, ifconfig shows similar packet rx and tx counts, and
zero error counts.
arping to the XP machine from the Red Hat machine is reliable and fast.
When we try a browser on the XP machine and address the web server on
the Red Hat host, there is generally a long pause (perhaps minutes),
then suddenly the page appears.
We have tried using another Linux box in place of the original XP
machine, with the same results from the Red Hat system.
We have tried replacing the cables and switch, with no effect - given
that arpings are working perfectly it's hard to see how it could be a
I'm not very familiar with Red Hat or a 2.2 kernel (my experience is
mostly with Debian and related distros, and with 2.4 and 2.6 kernels).
But "ipchains -L" shows no firewalling (everything accepted), "ifconfig"
and "route -n" have the expected setup, and I could not stop anything
unexpected with "sysctrl".
One of my colleagues will try a different network card this evening.
Any ideas or tips would be much appreciated. We've tried pretty much
every sensible idea we can think of, so I'm ready to listen to any crazy
or unlikely tricks.
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