Strange RAW Socket on Mac OS X

Question

When i run a simple packet sniffer coded in C on my Mac OS X, i got no output at all, this is a strange thing! can someone help me to understand what going on.

Answer 1

I run it and get:

# ./a.out
Got some bytes : 176
Got some bytes : 168
Got some bytes : 168
# 

I'm guessing it's going to be something really odd, like you don't have permission to open a socket and stderr is redirected oddly.

I'd suggest the good old-fashioned wolf-trap debugging:

   printf("I got ti 1\n");
   if ((sockfd = socket(PF_INET, SOCK_RAW, IPPROTO_TCP)) == -1) {
        printf("Socket failed!!\n");

        return -1;
   }
   printf("I got to 2\n");
   for(i=0; i < 3; i++) {
      printf("About to read socket.\n");
      recv_length = recv(sockfd, buffer, 8000, 0);
      printf("Got some bytes : %d\n", recv_length);
   }
   printf("Past the for loop.\n");

...and see what it says.