Nevertheless, the same machinations that allow for transparency in Plan 9 disallow certain functions that can be naturally provided by a NAT implementation, or any of a number of software categories that involve packet filtering/rewriting/inspection. For example, the one I referred to in the posting you have quoted in your response: load balancing. Add to the list: rate control, intrusion detection, QoS earmarking, honeynetting, et cetera ad [put you favorite -um, -am here].
I wouldn't go so far as to say Plan 9 "disallows" certain functions that are implicit in NAT. As someone mentioned in the thread before, it is certainly possible and rather easy to write something similar to trampoline(8) to perform load balancing. Add in packet analysis to the mix and you have rate control, intrusion detection etc.
Plan 9, in the end, is infinitely more malleable than most other OSes :-)
-- Anant
