Winpcap simple question - how to send packets to a specified ip/port?

Question

I read the tutorials and so, but I am not getting it. It does let you send packets, but how can you tell Winpcap where to send those packets? Is there any header I should put on the packets so it will know to which ip/port's to forward it? I mean. Let's imagine I want to send some data to my MSN, as if I had wrote something to someone on my list. I can use the sendpacket(), but it will only take the packet/byte array as argument, not specifing to which app/ip/port so send it.

Thanks

Answer 1

You don't tell Winpcap where to send packets. You tell it to put a packet on the wire. The network switch will send the packet to the right destination. The TCP stack on the receiving end will send the packet to the right application/service. Obviously this means the routing information has to be in the packet itself.

To take your example, you'd need to put the IP address and TCP port of the appropriate MSN server in the packet. If you don't, your networking hardware will discard or misroute that packet.