[LARTC] NAT+portfw failure

[Paul Wouters paul@xtdnet.nl]

<PRE>I have the following forced up mew by evil telco problem:

- One IP
- Homebrew LAN
- portforwarding for some services.
- extra PPTP/ppp layer to an internal 10.* network which mutilates DNS
  answers.

Setup:

Machine A has ip a.b.c.d (real IP) and is reachable over ADSL with it from
the world. It does NAT for an internal LAN 192.168.0.0/24) and has portforwading
turned on for some ports (eg 80) to 192.168.0.x. The pptp interface has 10.c.d.e.

Problem: When on the LAN, pointing to www.whatever.nl resolves to a.b.c.d for
everyone, but the Telco's stupid system rewrites it to be 10.c.d.e. A packet
is sent with source 192.168.0.y and destination 10.c.d.e. It arrives a the
firewall, get's NATTED, and portforwarded. However, the portforwarded
destination is on the same interface as the packet came from, and this then
generates an icmp unreachable.

Is there a way to allow this (on linux 2.2). If not, would 2.4 NAT of the
destination address work or have the same simmilar interface problem?

Paul, who realises he is too tired to better explain &quot;MXstream, KPN's
wonderful horrible ADSL network&quot;

-- 
Just patent your virus and sue the anti-virus companies for reverse
enineering it.
                  --- <A HREF="mailto:cne_pc@youknowwhattodo.yahoo.com">cne_pc@youknowwhattodo.yahoo.com</A>, in response to Norton's
                      patent on &quot;software updates&quot;



</PRE>