#include <net/if.h>
#include <linux/if_tun.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>

int tun_alloc(char *dev, char *command, char *type)
{
struct ifreq ifr;
int fd, err;

if( (fd = open("/dev/net/tun", O_RDWR)) < 0 )
{
  perror("opening /dev/net/tun for read/write");
  return fd;
}

//Give ifr the proper amount of memory space
memset(&ifr, 0, sizeof(ifr));

/* Flags: IFF_TUN   - TUN device (no Ethernet headers) 
*        IFF_TAP   - TAP device  
*
*        IFF_NO_PI - Do not provide packet information  
*/ 
if (strcmp(type, "TUN") == 0)
{
   ifr.ifr_flags = IFF_TUN; 
}
else
{
   ifr.ifr_flags = IFF_TAP;
}
//Set device name
if( *dev )
{
 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
}

//Access file descriptor for TAP/TUN interface
if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
 close(fd);
 return err;
}

//Create interface by enabling persistence on it
if (strcmp(command, "create") == 0)
{
   if( (err = ioctl(fd, TUNSETPERSIST, 1)) < 0){
     perror("enabling TUNSETPERSIST");
     return err;
   }
}
//Or delete existing interface by disabling persistence
else
{
   if( (err = ioctl(fd, TUNSETPERSIST, 0)) < 0){
     perror("disabling TUNSETPERSIST");
     return err;
   }
}

return fd;
}

int main(int argc, char* argv[])
{
 if (argc < 3 || ((strcmp(argv[1], "delete") != 0 && strcmp(argv[1], "create") != 0)) || ((strcmp(argv[3], "TUN") != 0 && strcmp(argv[3], "TAP") != 0)))
 {
   printf("Usage: <program_name> create|delete <interface_name> TUN|TAP\n");
   return 0;
 }
 char tun_name[IFNAMSIZ];
 char tap_name[IFNAMSIZ];
 char *a_name;
 strcpy(tun_name, argv[2]);
 int response = tun_alloc(tun_name, argv[1], argv[3]);
 if (response < 0)
 {
   printf("Couldn't create interface. Make sure you're running as root\n");
 }
 return 0;
}