Re: Entirely ignoring TCP and UDP checksum in kernel level

From: Brad Campbell
Date: Sun Aug 22 2004 - 04:40:43 EST


Josan Kadett wrote:
Bad news... NAT does not work, but it should have worked. Where might be the
mistake ? I put another machine connected next to the patched linux server,
I sniff the traffic and see that:
(I enabled SNAT);

Packet arrives from 192.168.0.30 (new machine to test nat)
The packet is correctly translated and sent over the line
With the patch, the new packet seems to arrive from correct source 77.1

*But this is where the problem begins, the system does not send the received
packet to the address which is SNATted. I thought, the ip_input.c code would
work in the lowest level so IPTABLES would naively use the changed source
address...

I do not know if ever this problem will end...



Client A 192.168.0.20 -- connects to patched linux server
Linux 192.168.1.1 -- translates the source address 192.168.x.x to

1.1(SNAT)

You have 192.168.0.x NAT to 192.168.1.1?
I thought you wanted to NAT to 192.168.77.1?

My understanding was you sent a packet to 192.168.77.1 and the device sent it back from 192.168.1.1

Can you send me your iptables configuration?
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