Subject: Re: AGAIN : does IPNAT work or not?
To: Olli <>
From: Guenther Grau <>
List: netbsd-users
Date: 02/13/1999 20:08:50
Hi Olli,

Olli wrote:
> -> NetBSD-box:
> -> Linux-box:
> -> telnet (
> 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 to
   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 -> 0/32 portmap tcp/udp 40000:60000
map ppp0 -> 0/32 

Try the following line as your ipnat.conf:

map ppp0 -> 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.