Obtain sender's MAC address for a UDP packet

[valery]

When I receive a UDP packet from a remote computer, I need to determine the MAC address of the (remote) interface card from which it was sent. Is there any way to do this?

[Scott.Bonomi]

It should be bytes 6..11 in the datagram.
I suggest you get wireshark and capture some of your actual packets to ensure they are being built correctly.

[Sprite]

Scott.Bonomi: You don't get the Ethernet-level packet if you use the sockets interface, which valery likely is doing.

Valery: The IP you're receiving from is associated with the MAC through arp. You might be able to use the LWIP call etharp_find_addr() or etharp_get_entry() to convert the IP back to the MAC.

[valery]

Valery: The IP you're receiving from is associated with the MAC through arp. You might be able to use the LWIP call etharp_find_addr() or etharp_get_entry() to convert the IP back to the MAC.

Thank You