Chris Jones <cjones@rupert.honors.montana.edu>,wrote on Apr 02, 1999 at 11:26 -0700: 
[snip]
> I'm trying to get NAT working with a 1:1 mapping of external to
> internal IP addresses.  I'd like to get it to pass through incoming
> connections to the appropriate internal IP.
> 
> I've got my NAT machine at 153.90.240.170, and I want to make it
> forward packets for 153.90.240.181 from de0 to 10.1.240.181 on de1.
> But, of course, if I "ifconfig de0 alias 153.90.240.181", the NAT
> machine starts accepting packets for the hidden machine.
> 
> If I use a "map" rule in ipnat.conf, it only works for outgoing
> connections.  Once the connection is established, packets can go in
> both directions; but I'd like it to allow incoming connections, too.
> 
> I can use "rdr de0 153.90.240.181/32 port 23 -> 10.1.240.181/32 port 23 tcp",
> but I have to specify that for each service on the machine.  Making
> things like NFS work becomes a real pain this way.
> 
[snip]
If you use port 0 all ports will redirected the way you want.

-- 
mvh Jens