NAT issue - answer packets not sent to default gateway

[Emre Bastuz]

Hi,

I have a FreeBSD box with four interfaces (actually four VLAN interfaces over
one trunk).

Packets from arbitrary IP addresses are supposed to arrive through interfaces
1-3 and the answer to those requests is supposed to be sent out on interface 4
(which is the default gateway).

Main goal is to create some kind of forced portal. To achieve this I´ve been
testing NAT rules, mainly this one:

rdr vlan220 0/0 port 80 -> 127.0.0.1 port 80 tcp

The translation itself works as expected so every http request is being forced
to the proxy machine itself:

bash-2.05b# ipnat -l
List of active sessions:
RDR 127.0.0.1       80    <- -> 198.133.219.25  80    [some.source.add.res 1098]

When the PC with the IP some.source.add.res fires up the browser and requests
http://www.cisco.com/ I would expect a different page to show up, namely the
index.html the Apache on 127.0.0.1 is configured to show.

However this does not happen as long a I do not have a host route for the
requesting PC on my proxy machine such as this:

bash-2.05b# route add -host some.source.add.res 192.168.0.1

(where 192.168.0.1 is the "other" side of a point to point link on one of the
interfaces 1-3).

Am I missing something? This is driving me nuts. Honestly.

TIA,

Emre

P.S.: net.inet.ip.forwarding=1

--
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I don't see why some people even HAVE cars. -- Calvin

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