> 
> My Questions:
> *************
> Can you give me the solution to:
> 	- why can I do A <-> C and B <-> C but not A <-> B (via C) ??
You haven't turned on IP forwarding.
> 	- what's the reason that C doest not forward all packets with 
> 	  destination other destination than C itself ?
You haven't turned on IP forwarding.

> 	- what's the solution to this problem, do you give it to me if
> 	  possible ?
> 
# sysctl -w net.inet.ip.forwarding=1

-- Ragge