From: "Lawrence A. Wimble" <law@dodinc.com>
To: linux-kernel@vger.kernel.org
Subject: Bizarre network issue
Date: Sat, 05 Oct 2002 19:10:33 -0400 [thread overview]
Message-ID: <3D9F7169.8020008@dodinc.com> (raw)
Greetings.....
I am working on a driver for generic serial-based radios (e.g, Coyote
Datacomm
DR-915 and Microhard MHX-910, etc..), that basically allows the radio to
be used
as a network interface, much in the spirit of STRIP. Kernel is 2.4.8
(mandrake 8.1).
Given that the radios pose an "unknown", I have gone to a NULL-modem cable
until this issue is resolved. Here's what *is* working across my interface:
1. ARP ... tcpdump shows both the request AND reply.
2. PING ... Getting approx 120ms round trip with the MHX-910s (23ms null
modem)
3. UDP ... Works perfectly with netcat in both directions.
Here's what *is not* working:
4. TCP .... tcpdump shows the SYN packet, but no SYN/ACK ever appears
5. ICMP 3/3 ... If I try a UDP session when there's no-body "listening"
on that
remote port, no "Port Unreachable" message is ever sent back to the
sending host.
The fact that items 1 though 3 work, indicate that 4 and 5 should work
as well,
but they don't. I have added a debug statement to my driver's
"hard_start_xmit"
routine to write to syslog when it's called. The kernel does not even
appear to
be calling the routine to respond to TCP SYN's or UDP packets headed for
an unreachable port.
The worst part of this is that TCP was working fine across this
interface about
a month ago. When I went to pick up where I left off from is when this
behavior
started to exhibit itself. Any ideas?
Please CC me personally on responses as I am not subscribed to the list.
TIA,
Larry
--
Lawrence A. Wimble 414 NE 3rd Street; Suite B
Chief Software Engineer Crystal River, FL 34429
Design On Demand, Inc. Phone 352-563-1225 x112
law@dodinc.com Fax 352-563-2098
next reply other threads:[~2002-10-05 23:00 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-10-05 23:10 Lawrence A. Wimble [this message]
2002-10-05 23:27 ` Bizarre network issue Alan Cox
2002-10-06 3:03 ` Mazhar Memon
2002-10-06 16:44 ` Alan Cox
2002-10-07 11:27 ` Lawrence A. Wimble
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