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SubjectTUN/TAP driver doesn't work.

I am trying to use TUN/TAP driver. My OS is RH71, kernel is 2.4.17, with
tuntap compiled as a module. Module is inserted properly when I try to
open '/dev/net/tun', and I get kernel message saying "TUN/TAP universal
driver, (c)...etc.". But ioctls don't work and always return '-1'.
To test it I was using code from tuntap's documentation (included below this
message and btw I don't understand dev's name str-copying in this code)
and pengaol, newest version, which I know works with tuntap. None of these
2 programs work for me.

Any help would be really greatly appreciated.


-- test code --
#include <sys/fcntl.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_tun.h>

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

if( (fd = open("/dev/net/tun", O_RDWR)) < 0 ) {
printf("open error\n");
return 0;

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
ifr.ifr_flags = IFF_TUN;

if( *dev )
strncpy(ifr.ifr_name, dev, IFNAMSIZ);

if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
printf("ioctl err %d: %s\n", err, strerror(err));
return err;
strcpy(dev, ifr.ifr_name);
return fd;

int main(int argc, char **argv)
char test[100] = "1234567890123456";
return 0;

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