* How can I edit data of packet before send or receive? I need to make program like "winsock packet editor". This program not only filter packets but it can edit data of packet before sendind or receiving packets. Please help me.

http://www.ethereal.com/

Download the source code for this packet analyzer/sniffer. It will show you what you need to make the appropriate network driver.

Specifically, you are looking for WinPCap.

ÔÕbut both ethereal and winpcap can capture and filter packets not edit packet. please tell me exacly programming to deal with packet data editor

I beleive he answered your question... if you check out the sources, it sniffs the packets BEFORE they are sent, then forwards them to the "real" network driver... if you intercept them, you can modify them, and forward it to the "real" network driver... same idea, check out the sources, and see how they work, and you''ll see that it IS what you want, because you intercept the packet, and can do what you want with it before you send it along on its way .

thank you everyone very much!!

Exactly. Just modify WinPCap to provide extensions or events that allow your application to modify the data before it is actually sent.

BTW What are you trying to accomplish? There might be an easier way...