Spoofing, Mascarade

IP: 
     +-------+------+------+---------------------------+
     | ..... | SRCE | DEST | (TCP or UDP)              |
     +-------+------+------+---------------------------+
             Unchecked!
1/2 connections: 
       Attacker    Target(Y)      Friend(X) 
        
    
		--------->
                   (process)
                   (reply)
                 
                       -------------->