In changing the code to be:
 -      if (nat->nat_dir == NAT_OUTBOUND) {
 +      if (oip->ip_dst.s_addr == nat->nat_oip.s_addr) {

a regression is introduced with "ni2".  I need to look at this
more closely to determine whether it is the regression test or
the code that is at fault.

"ni2" tests an ICMP NEED FRAG being generated in response to an
incoming packet that we pretend is too large.

Darren