ipfw nat proxy rules

[Beastie]

Hi list.

I would like to put a question about ipfw nat proxy rules. man page
say's that there is "proxy_only" rule available.
I know that ipfw nat use the same libalias like natd do. man page por
natd say that we can use "proxy_rule" to define proxing settings, but
I do not see this option in ipfw nat man page.

Is proxing is implemented in ipfw nat? How to use it (is "proxy_rule"
available)?

Thanks.