title: get IP Address of source in datagramsocket in Java
body: <p>I have a <code>DatagramSocket</code> via which UDP packet are sent from client to server and <em>vice versa.</em> I have to include IP source address in reply packet to client. Is there a way to obtain such as IP address using Java?</p>
  
  <p>I add some clarification
  I have no control in UDP client, this is a thirt party client. I can only have control in UDP server. So I cannot use DatagramPacket.getAddress() in client source code but only in server source code.
  I know that is not necessary  to include IP Address source in the datagram packet since the source IP address is always available to the receiver (from UDP header I think) but in my case I have sort of handshake between client and server so I have to include server Address in UDP payload data.</p>
  
  <p>CLIENT 192.168.x.x  send UDP packet to SERVER 192.168.255.255:8010 
  in reply to this server should send back to client a replay datagramPacket in wich I should Add the server address (es 192.168.y.y)</p>