Hi List
I trying to open my own raw PF_PACKET socket to receive

pkgs sent to this socket. I can only make ETH_P_ALL protocol

work, but then I receive all pkgs and I want pkgs with a specific

protocol type. I have tried lots of ETH_P types and none of them work.

Naturally I make sure the sender is using the same protocol as my test

program below. I guess I must be doing something wrong???
Here is the test program:
#include

#include

#include

#include

#include

#include

#include 
int main(int argc, char **argv) {

  int sock, n;

  char buffer[2048];

  unsigned char *iphead, *ethhead;
  if ( (sock=socket(PF_PACKET, SOCK_RAW,

                    htons(ETH_P_IP)))<0) { // ETH_P_IP is just an example

    perror("socket");

    exit(1);

  }
  while (1) {

    printf("----------\n");

    n = recvfrom(sock,buffer,2048,0,NULL,NULL);

    printf("%d bytes read\n",n);
    /* Check to see if the packet contains at least

     * complete Ethernet (14), IP (20) and TCP/UDP

     * (8) headers.

     */

    if (n<42) {

      perror("recvfrom():");

      printf("Incomplete packet (errno is %d)\n",

             errno);

      close(sock);

      exit(0);

    }
    ethhead = buffer;

    printf("Source MAC address: "

           "%02x:%02x:%02x:%02x:%02x:%02x\n",

           ethhead[0],ethhead[1],ethhead[2],

           ethhead[3],ethhead[4],ethhead[5]);

    printf("Destination MAC address: "

           "%02x:%02x:%02x:%02x:%02x:%02x\n",

           ethhead[6],ethhead[7],ethhead[8],

           ethhead[9],ethhead[10],ethhead[11]);
    iphead = buffer+14; /* Skip Ethernet header */

    if (*iphead==0x45) { /* Double check for IPv4

                          * and no options present */

      printf("Source host %d.%d.%d.%d\n",

             iphead[12],iphead[13],

             iphead[14],iphead[15]);

      printf("Dest host %d.%d.%d.%d\n",

             iphead[16],iphead[17],

             iphead[18],iphead[19]);

      printf("Source,Dest ports %d,%d\n",

             (iphead[20]<<8)+iphead[21],

             (iphead[22]<<8)+iphead[23]);

      printf("Layer-4 protocol %d\n",iphead[9]);

    } else {

       int i;

       iphead = buffer+12;

       for(i=0; i