I have a client and a server which sends a UDP broadcast to 255.255.255.255 to notice their existence. On some computers, when the client and the server is running on the same machine, the UDP broadcast will fail. It works if the client and the server is on different machines.

However, if WinDump (http://www.winpcap.org/) is running with WinPcap installed on the computer, the UDP broadcast works when the client and the server is on the same computer.

Why does the broadcast work on the local machine when I run WinDump? Can I make the broadcast work without this third-party software? Is it related to the network card since it works flawless on some computers?


Fredrik