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Is there any way to get current wireless SSID without root permission?

iwconfig tells me ESSID, but only if I run it as root.

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What happens if you run it as a regular user? What Linux distribution do you use? Also, you may find Unix & Linux a more suitable site for such questions. –  Lev Levitsky Sep 1 '12 at 20:09
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closed as off topic by nandeesh, John Palmer, joran, DCoder, jonsca Sep 2 '12 at 6:56


1 Answer

up vote 3 down vote accepted

If you take a look at the source code of the iwconfig (wireless_tools), you'll see this line:

iwconfig.c:639: if(iw_get_ext(skfd, ifname, SIOCGIWESSID, &wrq) < 0)

This line is responsible for the get of ESSID (wireless.h). And i think that only root have permissions (out of the box) to do this, so the function iw_get_ext (defined in iwlib.h from wireless_tools package) which call ioctl will return EPERM (Operation not permitted).

 * Wrapper to extract some Wireless Parameter out of the driver
static inline int
iw_get_ext(int                  skfd,           /* Socket to the kernel */
           const char *         ifname,         /* Device name */
           int                  request,        /* WE ID */
           struct iwreq *       pwrq)           /* Fixed part of the request */
  /* Set device name */
  strncpy(pwrq->ifr_name, ifname, IFNAMSIZ);
  /* Do the request */
  return(ioctl(skfd, request, pwrq));

You have 2 solutions:

  1. Use the setuid to allow the user to use iwconfig command:

    sudo chmod u+s /sbin/iwconfig

  2. You can also try to do some hacking with the CAP_NET_ADMIN capability which allow some specific capabilities to a specific user. Here some links about CAP_NET_ADMIN:





Finally you can use strace to trace all system calls and to confirm that ioctl call is the responsible for this:

as root do this:

#strace /sbin/iwconfig your_interface_name > strace_iwconfig_root.log

And the same as normal user:

$strace /sbin/iwconfig your_interface_name > strace_iwconfig_normal.log

And compare the results.

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Great! chmod u+s or doing something with CAP_NET_ADMIN and CAP_NET_ADMIN both work very well. Thank you very much! –  npcode Sep 3 '12 at 15:23
@npcode : ok thanks, you're welcome. –  TOC Sep 3 '12 at 15:32
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