Is there anyway to keep a broadcast packet within a subnet rather than it being sent all over the internet?
Uhm, I think that ISPīs are required to stop broadcast messages, and not send them along. However, when I send a broadcast udp packet, my isp replies to me (who knows, maybe to all users of myisp), Im fairly confident however, that no one else gets them, Cheers, J.Ahner
If you want to broadcast to all addresses on 192.168.20.xxx, and your subnet mask is 255.255.255.0, all you do is use 192.168.20.255 as the destination address, and that should broadcast to all addresses on the subnet. If your subnet mask is 255.255.0.0 and the address range is the same again, use 192.168.255.255 as the destination address, and so on. You basically need to set all the bits that are outside the subnet mask of the address to 1. Hope this is useful Nick
Thanks, Nick. Your information was very useful.
FYI: that's a class "c" format... which IS the most common senario. I haven't gotten too deep into this just yet & haven't tried the "a" & "b"... i'll be sysman at the new job (truely scary they'll let me) & i'm learnin' up so i can test for hacker probes. The world has gotten a lot more complicated since 802.3, 802.4, 802.5 were all i had to know... so much to learn so little time for assembler :(