Question

I have a small FPGA that needs to communicate with a C program running on a Ubuntu Machine via ethernet. The FPGA is too small to use TCP etc. I can send frames and pick them up in wireshark using just the MAC address of the ethernet port but to communicate with the C I need to use a RAW Socket however in creating the socket it needs a protocol value, is there any protocol that would allow me to communicate solely using the MAC address.

The frames have the following structure

Destination MAC address
Source MAC address
Protocol - 0x55aa
Data 

Answer 1

If you use PF_PACKET instead of PF_INET then your 0x55aa value is your protocol number:

#include <sys/socket.h>
#include <netpacket/packet.h>

packet_socket = socket(PF_PACKET, SOCK_RAW, ntohs(0x55aa));