Hiya,

After spending a bit of time pulling my hair out, I have realized that under
the configuration I'm using (NetBSD-1.3/i386), ipnat doesn't work unless ipf
is enabled.

Maybe this is obvious to some, but I think that it would be a good thing if: 

1.  ipnat would warn you that its not going to be doing any mapping until you
run "/sbin/ipf",

and/or

2.  Something should be said about this in the man page for ipnat(8).

eg "Please note that ipnat will not actually rewrite any packet headers unless
the ipf packet filter is active." 

Mentioning in the ipnat(8) man page which kernel options are required to make
nat go zoom would be handy as well. 

EJR