Subject: Re: AGAIN : does IPNAT work or not?
To: Olli <firstname.lastname@example.org>
From: Guenther Grau <Guenther.Grau@bk.bosch.de>
Date: 02/13/1999 20:08:50
> -> NetBSD-box: 192.168.1.1 netbsd1.network.de
> -> Linux-box: 192.168.1.2 debian1.network.de
> -> telnet 188.8.131.52 (physik.phy.tu-dresden.de)
> I append the output from "tcpdump -i ppp0" and my ipnat.conf - file. I
> hope someone can help me.
There are several problems with this tcpdump:
1) You didn't use all the options I asked you to (-v -v -x -s 1500 are
2) You seem to have several connections from the netbsd-machine (I
this is dialup-250.dresden.nacamar.de) to physik.phy.tu-dresden.de.
This makes it unneccessary harder to see what's actually going on.
Please keep the examples/test cases as simple as possible. That way
people can have a short look on it and easily spot what's wrong.
3) You should have used the option -n to tcpdump, which prevents
lookups. This wasn't your fault as I didn't tell you :-)
4) The tcpdump from the other interface to the linux machine is missing.
Nevertheless after reading through the tcpdump I figured that the netbsd
isn't sending anything from the port range 40000:60000. That means that
request from the linux machine doesn't get translated at all. This is
probably due to you ipnat.conf file:
map ppp0 192.168.1.0/24 -> 0/32 portmap tcp/udp 40000:60000
map ppp0 192.168.1.0/24 -> 0/32
Try the following line as your ipnat.conf:
map ppp0 192.168.1.0/24 -> 0.0.0.0/32 portmap tcp/udp 40000:60000
For further reading I suggest you go to
And follow the link to the NAT FAQ. Read it carefully. If you still
any problems afterwards, please feel free to come back with a simple
test case to show what doesn't work.
Hope this helps,
P.S.: Please don't send me a personal copy of the emails. I am on this
and will read any mail sent to this list.