Question regarding packet src/dst rewriting

[Samuel Jean]

On Fri, August 20, 2004 12:32 pm, Russell Handorf said:
> The weird behavior I am having is that whenever a packet from the
> Internet comes in interface eth0, and gets forwarded to a server on
> eth1, the server which resides on the eth1 side of the network sees the
> source IP as coming from the router and not the real host on the
> Internet. Vice versa applies as well (a node behind eth1 sends a packet
> out to, say, google.com. Google.com sees the data as coming from the
> router, and not the node which is behind eth1).
>

My assumption is that you are using a MASQUERADE rule regardless of the
outgoing device.

> I dont understand why the packet headers are being re-written. I also
> dont understand if this is a specific problem with iptables, or the
> linux kernel itself.
>
> eth2 and eth3 are masquerading, but eth1 is not.
>

Okay, so you are using 2 MASQUERADE rules with specific outgoing device ?
Please post your ruleset. PREROUTING and POSTROUTING chains should be eno=
ugh.