Re: UDP Broadcast message when system has more than one network card

"Mark Salsbery [MVP]" <MarkSalsbery[MVP]@newsgroup.nospam>
Fri, 7 Mar 2008 16:45:58 -0800
"amccombs" <> wrote in message

I have an application that broadcast a UDP pack to all devices for reply.
When a system has more than one network card it seems to only broadcast it
only on the first card that was installed in the machine. How do I get it
broadcast on all network devices on my system?

I am using,

Create(0, SOCK_DGRAM);
BOOL bMultipleApps = TRUE;
SetSockOpt(SO_REUSEADDR, (void*)&bMultipleApps, sizeof(BOOL), SOL_SOCKET);
SetSockOpt(SO_BROADCAST, (void*)&bMultipleApps, sizeof(BOOL), SOL_SOCKET);

SendTo(pBuffer, nSize, nPort, NULL, MSG_DONTROUTE);

Have you tried using bind() to bind your socket to the address of a specific
adapter (instead of INADDR_ANY)?

GetAdaptersInfo()/GetAdaptersAddresses() can help to enumerate the available
adapters and their associated addresses.

A search on "multihomed host socket" yields a lot of info :)


Mark Salsbery
Microsoft MVP - Visual C++


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