Hi all, :)
How to broadcast a message within a LAN using Winsock? Meaning how to send a message to every machine in a local network without knowing their IP addresses, of course you do know the port you’re using. Like when games find all servers in a network without knowing they are there.
You can use Internet Group Management Protocol to issue multicasts. There is some stuff at MSDN here or search google.
multicasts? isn't that diffrent from broadcast?
I have heard that you can also use UDP, is that true? If so then how?
>>> multicasts? isn't that diffrent from broadcast?
On IPv4 Class A, B and C addresses, filling the host fields with all "1"'s will "broadcast" to all listening stations on that network. A true "multicast" uses Class D adresses and can be made to do the same thing within a network.
The bottom line really is that Class D addresses are problematic and there have been various suggestions as to the correct way forward. Broadcast, multicast you pay's your money and takes your choice.
Searcg google for IPv4 address formats if you are interested in the details.
With UDP there is no guarantee what you send will get to where you send it, and if it doesn't you will not be told. UDP is very crude, (read the RFC, (RFC-768) - it is only 3 pages! - most others have a table of contents longer than that!)
Where is the RFC or (RFC-768) ??
There are dozens of sites that catalog internet RFC's - run the above search.