> I wonder what is exactly advantage of 'pf' over 'ipf'. Perhaps you
> could summarize differencies?
> 
I think important (even if nontechnical) differencies are:

- pf is BSD licensed, 

- there seems to be more active developement on pf.

And in the future , there are plans to integrate ALTQ and pf (work has
already begun). Right now, the syntax for ALTQ's filters is neither as
intuitive nor as powerful as the syntax for pf or ipfilter, and it's
a good idea to not have two filters, one for firewall and other for
ALTQ. I'm not aware about such project for ipfilter.

Pavel