Destination MAC address

Sep 13, 2012 at 7:02 AM

Hello! I've a question about the destination MAC address when i create a packet. If i don't know it, what i can assign at this variable?

Thanks!

Sep 13, 2012 at 7:33 PM

Anyone has a response?

Sep 14, 2012 at 9:52 AM

Excuse me, but I don't understand why I've to know the destination MAC address to send packets to a remote system in Internet.

Coordinator
Sep 14, 2012 at 10:43 AM

You can put whatever MAC address you want, it depends what kind of packet you want to send.

Normally, Ethernet networks use ARP protocol to get the correct MAC address. See http://en.wikipedia.org/wiki/Address_Resolution_Protocol

Sep 14, 2012 at 10:49 AM
Edited Sep 14, 2012 at 10:50 AM

Thank you for the response!

I've to send packets to a remote system in Internet, not in a LAN. The type of packet is UDP.

Can I write, for example, 11:22:33:44:55 in the destination MAC address, or with this value I will have problems in the trasmission?

Thanks!

Coordinator
Sep 14, 2012 at 10:53 AM

If your packets are UDP over IPv4 over Ethernet, it depends on the router connected to your computer.

If that router will be willing to route these packets even though they are not marked to be sent to him over Ethernet in the MAC address, it would work.

If not, you better find out what is the router MAC address using ARP or manually.

Sep 14, 2012 at 11:02 AM

Excuse me, but at this point I've a very big question, ehm, the destination MAC address, is the address of my router or the address of the remote system on the WEB?

Coordinator
Sep 14, 2012 at 11:15 AM

The destination MAC address is the MAC address of the network device directly connected to your computer via a LAN Ethernet network.

It is the device that will route your packet to the next device (that already has a different MAC address).

The routing between devices is done using the IP address, the routing within a LAN is done using a MAC address that the devices get by translating the IP address to a MAC address using ARP.

I recommend reading a bit about how do Ethernet and IP work.

Sep 14, 2012 at 11:22 AM

Thanks!