dbd643df   
   From: philip+usenet@paeps.cx   
      
   dbtouch  wrote:   
   > Here is the list to sum up what I want to do:   
   >   
   > Create a RAW socket and send a multicasting UDP packet to it.   
      
   Why would you insist on using a raw socket?  Why not just use a UDP socket?   
   What benefit do you you think you will gain from using a raw socket rather   
   than an UDP socket?   
      
   > 1. How to set the length of the datagram correctly?   
      
   If you're using a raw socket and including the IP header, you will need to set   
   the the total length field to the length of the header plus the length of any   
   data and options.   
      
   > 2. How can I set the socket option for raw socket to be broadcasting?   
   > 3. Does the multicasting group work in the same way?   
      
   For sending, there is no difference and I don't think you need any socket   
   options. If you want to receive multicast traffic, you will need to join the   
   multicast group on which you want to receive traffic.   
      
   > I am thinking to open a raw socket and recvfrom it and the inspect the   
   > packet for the IP header. Is it a good way?   
      
   That's receiving.  You mention earlier that you want to send?   
      
   > What I am facing is to reduce as much latency as possible to write a   
   > customized message system on the same network segment. I figure raw   
   > udp is the way to go.   
      
   What do you think "raw UDP" is?  How does it differ from "UDP"?  I still can't   
   see why you want to use raw sockets.  It looks like you just want to send UDP.   
      
    - Philip   
      
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   Philip Paeps                                    Please don't email any replies   
   philip@paeps.cx                                     I follow the newsgroup.   
      
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