libpcap : SIOCGIFHWADDR: No such device

Hello. I've just started using libpcap lib and been following some tutorials.

Code:

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#include <pcap.h>
#include <stdlib.h>
#include <stdio.h>

void dump(const unsigned char *data_buffer, const unsigned int length);
void pcap_fatal(const char *failed_in, const char *errbuf);

int main() {
  struct pcap_pkthdr header;
  const u_char *packet;
  char errbuf[PCAP_ERRBUF_SIZE];
  char *device;
  pcap_t *pcap_handle;
  int i;

pcap_handle = pcap_open_live(device, 4096, 1, 0, errbuf);
if(pcap_handle == NULL)
  pcap_fatal("pcap_open_live", errbuf);

for(i=0; i < 3; i++) {
      packet = pcap_next(pcap_handle, &header);
      printf("Got a %d byte packet\n", header.len);
      dump(packet, header.len);
  }
  pcap_close(pcap_handle);
}

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Code:

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xyz@ubuntu:~/Desktop/Programs$ gcc -o sniff libpcap.c -l pcap
xyz@ubuntu:~/Desktop/Programs$ ./sniff
Fatal Error in pcap_open_live: socket: Operation not permitted
xyz@ubuntu:~/Desktop/Programs$ sudo ./sniff
Fatal Error in pcap_open_live: SIOCGIFHWADDR: No such device

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Apparently pcap_live_open() keeps returning NULL, therefore the error I don't quite understand. I went over dozens of topics searching for solution, but couldn't quite find it.

As far as I get it, SIOCGIFHWADDR is an interface hardware address but I'm not sure what it's all about.

Thanks in advance,

Mercurial

Code:

---

  char *device;
  pcap_t *pcap_handle;
  int i;

pcap_handle = pcap_open_live(device, 4096, 1, 0, errbuf);
if(pcap_handle == NULL)
  pcap_fatal("pcap_open_live", errbuf);

---

Where?

Garbage in, garbage out as the saying goes.

Right. Thanks for that.

Code:

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#define DEVICE_SIZE 1000
// ...

device = (char*) malloc(DEVICE_SIZE*sizeof(char));

pcap_handle = pcap_open_live(device, 4096, 1, 0, errbuf);
if(pcap_handle == NULL)
  pcap_fatal("pcap_open_live", errbuf);

---

Same error though.

How about some meaningful string, not just creating variables with the right type just to make the compiler STFU.

Like

pcap_handle = pcap_open_live("/dev/this/is/my/device/I/want/to/open", 4096, 1, 0, errbuf);

If I actually understood the device part, I wouldn't be posting this topic.

The other name for this one is SIGIOWTF?ADDR ;)

Quote:

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Originally Posted by Mercurial

Hello. I've just started using libpcap lib and been following some tutorials.

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Apparently not the right one :rolleyes:

Quote:

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Originally Posted by Mercurial

If I actually understood the device part, I wouldn't be posting this topic.

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Here's the tutorial I used to write a packet sniffer with libpcap:

Programming with pcap

That was a few years ago and I don't remember much, but if you open that page you'll see the second subsection, "Setting the device":

Quote:

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This is terribly simple. There are two techniques for setting the device that we wish to sniff on. The first is that we can simply have the user tell us. [...] The other technique is equally simple. Look at this program:

Code:

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dev = pcap_lookupdev(errbuf);

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In this case, pcap just sets the device on its own. "But wait, Tim," you say. "What is the deal with the errbuf string?"

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Thanks alot.