Question

I’m learning how to work with raw sockets in Linux. I’m trying to create a socket like that:

if ((sd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
    perror("socket() failed");
    exit(-1);
}

But all I got after launch is:

socket() failed: Operation not permitted

I know that only root can create raw sockets, but if I run it with SUID bit or sudo – the
problem is the same. What’s wrong? The system is Ubuntu 11.04.

Maybe I’m including needless headers?

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h>
#include <netdb.h>
#include <sys/time.h>
#include <signal.h>
#include <unistd.h>

And I’m wondering – why SUID is useless?

Answer 1

My money on you not running your code correctly.

I’ve copied and pasted your exact code into an empty main(). I get the same error if I run it as myself, but it runs correctly under sudo. This is on Ubuntu.

The code:

#include <sys/socket.h>
#include <netinet/in.h>

int main()
{ 
  int sd;
  if ((sd = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
    perror("socket() failed");
    return -1;
  }
  return 0;
} 

Run as myself:

aix@aix:~$ ./a.out 
socket() failed: Operation not permitted
aix@aix:~$

Run as root:

aix@aix:~$ sudo ./a.out 
aix@aix:~$