so many thanks for replys, here I am planning to using pfsense to distributing internet connection in a building, i need firewall and trafic shaper
(is important have traffic shaper to control p2p connection), the reaim is a solution to enable sound conversation in msn messenger, or I am
wrong ?

You are most likely correct but this is a linux specific program.  pfSense is not linux.

This proxy is designed to transparently intercept AIM client messages and pass them through a configurable filter/rewrite chain. This allows selective modification of the source address provided in direct-connection setup packets, and so remote users can be told to use the global internet routable address, rather than the actual IP address of the client on the local network."

http://www.reaim.org/

Basically if your in an apartment building which everyone is using the same connection and everyone has non-routable addresses and more than one person wants to use the direct-connect functionality aim gets a little confused and this allows for changing of the ip address when direct-connect sessions are established from the buitlin provided local address to the outside ip address.