> I believe the same mtu/mss issues may be causing problems with ipnat as
> well. If I set the MTU on my iBook (running MacOS 10.1, sitting behind my
> NetBSD/i386 NAT box) to 1452, things seem to work more reliably than if it's
> set to 1500.

Additionally, there's some weirdness with the way ipf/ipnat handles
interacts with pppoe.. If NAT is initialized before the pppoe link comes up,
nat doesn't work; I have to reset ipf and ipnat (ipf -Fa -f /etc/ipf.conf,
ipnat -C, ipnat -F, ipnat -f /etc/ipnat.conf) to make it go again. This was
not the case with regular ppp links.

~ % cat /etc/ipnat.conf
map pppoe0 192.168.0.0/24 -> 0/32 portmap tcp/udp 40000:60000
map pppoe0 192.168.0.0/24 -> 0/32

In the interim, I'll try to hack my startup scripts so that ipnat starts
after pppoe..

Cheers,
George