Reading from the Ethernet card.

Hello to all.

I'm developing a simple sniffer using, for now, the library set: libpcap. I'm using this functions to open the socket for reading.

Code:

---


        int sock;
        char *dev;
        char errbuf[PCAP_ERRBUF_SIZE];

        /*Find the Ethernet interface*/
        dev = pcap_lookupdev(errbuf)); 
       
        /*Show the interface name found*/
        printf("Reading from: %s\n",dev);
       
        /* Open the socket to read only Ethernet frames*/
        sock=socket(PF_PACKET,SOCK_RAW,htons(ETH_P_ALL));   
       
        /* Associate the socket to the interface found */
        setsockopt(sock,SOL_SOCKET,SO_BINDTODEVICE,dev,strlen(dev));

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This is working fine, but the problem is that my PC has two interface cards (eth0 and eth1). I would like to choose the card I want to sniff and function pcap_lookupdev() only returns the first one it finds to be up.

Is there another way to achieve this?

Thanks!

Hey I found the way to get the list of interfaces. Here is how (for for those interested in the subject)

Code:

---


/* Show the list of interfaces to the user. */
void
show_interfaces(void)
    {
          pcap_if_t *interface_list;
          pcap_if_t *if_list_ptr;
          int result;
          int i;
          /* Ask libpcap for the list of interfaces */
          result = pcap_findalldevs(&interface_list, errbuf);
          if (result == -1) {
                fprintf(stderr, "%s\n", errbuf);
                exit(1);
          }
          /* Show them to the user */
          if_list_ptr = interface_list;
          i = 0;
          while (if_list_ptr) {
                if (if_list_ptr->description) {
                    printf("%d. %s (%s)\n", i, if_list_ptr->name,
                            if_list_ptr->description);
                }
                else {
                    printf("%d. %s\n", i, if_list_ptr->name);
                }
                if_list_ptr = if_list_ptr->next;
                i += 1;
          }
          pcap_freealldevs(interface_list);
      }

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oh, that is really cool, I need this kind of stuff ..

good days...