LinuxQuestions.org - Problems to bring up a TUN interface

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Problems to bring up a TUN interface

ifconfig tun0 10.0.0.1 255.255.255.0 up
gives error saying

SIOIFADDR tun0 no such device
I have installed the latest RPM.

Peter

I have installed an new RPM.. i still face the same problem

[root@localhost root]# modprobe tun
[root@localhost root]# lsmod | grep tun
tun 5696 0 (unused)
[root@localhost root]# ifconfig tun0 10.0.0.1 netmask 255.255.255.0 up
SIOCSIFADDR: No such device
tun0: unknown interface: No such device
SIOCSIFNETMASK: No such device
tun0: unknown interface: No such device
[root@localhost root]# uname -r
2.4.20-8
[root@localhost root]#

I checked documentation in kernel source, copied an example code and added includes to compile (frankly, I also changed error handling to compile, but it is not so interesting). While the program runs (after it has issued ioctl), tun0 exists. So if you want a program to use tun, this program should call tun_alloc before configuring tun0 interface. This way it will already have its pipe end to get data and tun0 created.

Code:

#include <stdio.h>

#include <sys/ioctl.h>

#include <linux/if.h>

#include <linux/if_tun.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include <stdlib.h>

#include <string.h>



int tun_alloc(char *dev)

{

    struct ifreq ifr;

    int fd, err;



    if( (fd = open("/dev/tun", O_RDWR)) < 0 )

      return -1;



    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 ){

      close(fd);

      return err;

    }

    strcpy(dev, ifr.ifr_name);

    return fd;

}              



int main()

{

        char ifname[] = "tun0";

        char s[1024];



        tun_alloc(ifname);

        printf("%s\n",ifname);

        scanf("%s",s);

}

Am getting compiling errors as
[root@localhost peter]# gcc mytun.c -o tun
In file included from mytun.c:3:
/usr/include/linux/if.h:86: field `ifru_addr' has incomplete type
/usr/include/linux/if.h:87: field `ifru_dstaddr' has incomplete type
/usr/include/linux/if.h:88: field `ifru_broadaddr' has incomplete type
/usr/include/linux/if.h:89: field `ifru_netmask' has incomplete type
/usr/include/linux/if.h:90: field `ifru_hwaddr' has incomplete type
[root@localhost peter]#

Am I right that just that:

Code:

#include <linux/if.h>

int main(){return 0;}

causes an error? And what does

Code:

rpm -qf /usr/include/linux/if.h

say?

Facing Same Problem

Hi Peter I am facing same problem how did you fix it?

/usr/include/linux/if.h:165: error: field 'ifru_addr' has incomplete type
/usr/include/linux/if.h:166: error: field 'ifru_dstaddr' has incomplete type
/usr/include/linux/if.h:167: error: field 'ifru_broadaddr' has incomplete type
/usr/include/linux/if.h:168: error: field 'ifru_netmask' has incomplete type
/usr/include/linux/if.h:169: error: field 'ifru_hwaddr' has incomplete type
Hello.c:48:2: warning: no newline at end of file

thanks in advance.

I fixed it by adding...
#include <sys/socket.h>
before
#include <linux/if_tun.h>
#include <linux/if.h>