Thank you all for responding to my IP translation query.

Just to let you know about my progress...
I tried to install IP Filter this weekend but failed.  I have a slightly 
bugfixed NetBSD 1.0 and tried to build the LKM.  The install script in
IP Filter just managed to do a few things of what was supposed to be 
needed (judging from the different scripts).
I patched/copied around manually and rebuilt the kernel, but it crash
at end of boot.
I tried to recompile the kernel with non-LKM support, but it failed
to find some function (don't remember the name now).

I gave up on it.  Since it is not included in 1.2, but will be included
in 1.3, I see no reason to install 1.2 and retry, the install script only
seemed to like 386.

I will wait for 1.3.  Is it likely to be released during 1997?