TIdMappedPortUDP = class(TIdUDPServer);

TIdMappedPortUDP is a TIdUDPServer descendant that implements a tunnel for connections to a remote computer system using the UDP protocol. 

TIdMappedPortUDP listens for connections on a designated host address and port number, and makes a surrogate connection to another server using a specified port number. This is useful for certain types of proxy programs. TIdMappedPortUDP also implements an event notification mechanism for new connection requests.