Re: Gateway NAT use locking up OS

From: John Spaith [MS] (jspaith_at_ONLINE.microsoft.com)
Date: 03/01/05 

Date: Tue, 1 Mar 2005 12:59:00 -0800

I've asked around and none of my coworkers are fimiliar with this problem.
(The giving out the DHCP packet address on the public interface is a known
issue but isn't causing this).

Some thoughts for further investigation:
* The IP addresses 192.168.0.1 and 192.168.221.58 might be confusing the
routing part if the subnet masks on the two interfaces allow for overlap.
* Run the CETK platform validation tests to rule out BSP/driver issues. 

-- 
John Spaith
Software Design Engineer, Windows CE
Microsoft Corporation
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This posting is provided "AS IS" with no warranties, and confers no rights.
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"David Varley" <David.Varley@cborn.com> wrote in message 
news:OY08HfeHFHA.400@TK2MSFTNGP14.phx.gbl...
>I have a Kontron ThinkIO with Kontron CE 4.2 BSP (modified CEPC) Industrial
> Controller, which has been working successfully for some time. The device
> has 2 Ethernet ports, and I've added the gateway components (NAT, ICS, 
> UPNP
> + IGD, firewall, DHCP allocator, etc). the private interface is set up as
> 192.168.0.1, and on that side is a Rockwell L34 PLC, statically assigned 
> at
> 192.168.0.2. I've configured port forwarding, so that from the public
> interface port 8080 TCP forwards to internal 192.168.0.2:80, also the
> EthernetIP port 44818 (TCP and UCP) are forwarded to the internal PLC.
> This works, such that when I point my external web browser at port 8080 on
> the public interface (DHCP allocated at 192.168.221.58), it brings up the
> startup page of the PLC's http interface. However thats all I see, the CE 
> OS
> immediately locks up. I don't get ant diagnostic debug messages on the
> serial port, and don't know what's happening. The lockup also happens when 
> I
> connect a laptop to the hub on the private side. It get DHCP allocation, 
> and
> I can ping devices on the public side (NAT translation works), but if I
> tracert I get 3 hits on the CE interface (192.168.0.1), then one from the
> device on the public side (eg 192.168.221.4) and then CE locks up again.
> I suspect something in NAT if forwarding to itself in a tight loop, but I
> can't diagnose with the debugger, as the BSP doesn't support KITL over
> serial, or VMINI with the two Ethernet interfaces in use, as far as I can
> ascertain.
> Does anyone have any suggestions here, have I missed something?
> One other clue, early on in bootup the CE box actually sends two DHCP
> packets (the second an offer) with a source address of 192.168.0.1 out 
> over
> the 192.168.221.58 public interface, which should never happen...
>
> Thanks for any assistance,
>
> David
>
>

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