program/binary ip filtering

[Kevin Hunter]

Hi All,

This may not be the correct list to ask this question, so please  
point me in the right direction in that case.

We are in the process of setting up a bastion host.  One of the  
things we'd like to do is to filter packets not only at the ip layer,  
but by what program is listening on a particular port.  Is this a  
possibility?

A quick 5 minute Google didn't provide me with anything noticeable,  
but that my just be my noobness in the *BSD world.  So play nice!  ;-)

Thanks for any suggestions!

Kevin