linuxnetwork-programmingpacket-sniffersdata-link-layer

Read data-link (MAC) layer packets in Linux


Which is the simplest/shortest/easiest way to read packets from data-link (MAC) layer on Linux?

Could someone give us a code snippet on how to do that?

Why do we need it? We are developing a network camera in which the gigabit chip implements only the data-link layer. Since we don't have resources to implement the IP stack, we need to exchange packets using only the MAC address.


Solution

  • Here is the code snippet I was looking for:

    #include <stdio.h>
    #include <stdlib.h>
    
    #include <sys/socket.h>
    #include <linux/if_packet.h>
    #include <linux/if_ether.h>
    #include <linux/if_arp.h>
    
    
    int main()
    {
            int s = socket(AF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
            if (s == -1)
            {
                printf("Error while creating socket. Aborting...\n");
                return 1;
            }
    
            void* buffer = (void*)malloc(ETH_FRAME_LEN);
            while(1)
            {
                int receivedBytes = recvfrom(s, buffer, ETH_FRAME_LEN, 0, NULL, NULL);
                printf("%d bytes received\n", receivedBytes);
                int i;
                for (i = 0; i < receivedBytes; i++)
                {
                   printf("%X ", ((unsigned char*)buffer)[i]);
                }
                printf("\n");
            }
            return 0;
    }