CODEWITHSUNDEEP
csocketsfile-descriptor
user1307697
user1307697

Reputation: 15

bad file descriptor in raw socket

I become use raw socket and i have this problem:

bad file descriptor

the code is:

#include<stdio.h>
#include<sys/socket.h>
#include <netinet/in.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <unistd.h>
int main(int argc, char **argv)
{
int fd; //file descriptor raw socket

int ioInt;

struct ifreq req; //struttura per la chiamata di ioctl

fd=socket(PF_INET, SOCK_RAW, IPPROTO_RAW);

if(fd==-1) {



if(errno==EPROTONOSUPPORT)
    perror("socket o protocollo non supportato dal dominio");
if(errno==EACCES)
    perror("mancano i privilegi per creare il socket");
if(errno==EINVAL)
    perror("protocollo sconosciuto o dominio non disponibile");
if(errno==ENOBUFS || errno==ENOMEM)
    perror("memoria non sufficente per la creazione del socket");

}

 strncpy (req.ifr_name, "eth0", sizeof(req.ifr_name) - 1);

 ioInt=ioctl(fd, SIOCGIFINDEX, &req);

 if(ioInt==-1) 
    perror("SIOCGIFINDEX");

return 0;

}

I must access to eth0 and want send e receive a packet in that. I use linux mint 12

Upvotes: 1

Views: 3236

Answers (1)

mah
mah

Reputation: 39797

You're failing to print an error when fd==-1 and errno is not one of the values you are looking for.

I ran your code (as a non-privileged user) and fd came back as -1 with errno == EPERM.

You're most likely not running as root. You must run as root to get a raw socket.

Upvotes: 3

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