Linux – “iw” and some of its commands do not return any output

debiandebian-wheezyhostapdlinuxwireless-networking

I've been trying to set up my ARM based computer so that it becomes
a hotspot and a client at the same time.

However all of the information I've found about such functionality mention
the iw command which seems to be crucial for me to solve the problem I'm having.

It does not seem to work properly for me.

When I type iw wlan0 info I get the error message command failed: No such device (-19).

Why is this happening?

I'm on Debian Wheezy.

EDIT: I have a fully functional WiFi dongle connected to the ARM computer. The WiFi dongle is the only connection to my network.

The Wifi dongle is based on RTL8188CUS.

IMPORTANT

I managed to get it to work briefly by doing the following:

Add contrib non-free to the first two sources in /etc/apt/sources.list

Run apt-get update
Run apt-get upgrade

Run apt-get install firmware-realtek

Connect wifi dongle

Run iw list, it works now.

Kind of off topic, but related to why I need IW to work, and I'll get back to IW after my explanation

The wifi dongle I have uses an RTL8188CUS chip, and according to RealTek's
release notes this chip should support mixed modes as of version 4.0.0_5967.2021201.

By mixed modes I mean Station+Station, Station+AP, Station+P2P.

Note: The mode "Station" is also refered to as "Managed"

I've been trying to figure out how to make this chip use the Station+AP for months now, however, old drivers have been installed on every system I've used and set up, until I found this (which I'm trying now): https://github.com/pvaret/rtl8192cu-fixes

I've found some more resources which I'll try later.

NOW, back to IW;

IW seems to stop working when the wrong drivers are used.

Even though I use the wrong drivers, I still manage to connect the Wifi dongle
to any network, but IW no longer recognizes the device.

IWCONFIG works fine, IFCONFIG works fine.

So I believe that the wrong drivers will cause commands such as iw dev to stop working.

Additional information: the module 8192cu is never loaded when following the installation steps in the GITHUB above.

I know, they are not for the same driver, but they should still work for 8188cu according to RealTek.

Best Answer

You need to install wireless_tools

Open a terminal and type the following commands:

aptitude install wireless-tools

Restart network services:

/etc/init.d/networking restart

Update

You need to add interfaces with iw

iw dev wlan0 interface add <name> type <type>

For wired connection:

iw phy phy0 interface add <name> type <type>

There are several modes supported. The modes supported are:

monitor
managed [also station]
wds
mesh [also mp]
ibss [also adhoc]

Example:

iw phy phy0 interface add moni0 type monitor
iw dev wlan0 interface add wlan0 type station

Related Solutions

Linux – Configure RTL8188CUS for AP and Client Mode with Hostapd

It depends on network cards. I do not own an RTL8188, so i cannot tell you off-hand, but I can show you how to find out.

You must issue the command

 iw list

and, among its abundant output, you will find something like:

Supported interface modes:
             * IBSS
             * managed
             * AP
             * AP/VLAN
             * monitor
    software interface modes (can always be added):
             * AP/VLAN
             * monitor
    valid interface combinations:
             * #{ managed } <= 1, #{ AP } <= 1,
               total <= 2, #channels <= 1, STA/AP BI must match
             * #{ managed } <= 2,
               total <= 2, #channels <= 1

AP mode is the Access Point mode, managed is the usual client mode, and this is for my card.

You must check that both AP and managed appear among the supported modes, then you must check the valid interface combinations: in my case, the first allowed combination is clearly that of a (simultaneous) AP and managed mode (but no more than one each), provided the same channel is used. It might be different in your case.

In order to make this work, you must have two distinct virtual interfaces on the same NIC. You do it as follows:

service network-manager stop
iw dev wlan0 del
iw phy phy0 interface add new0 type station
service network-manager start
iw phy phy0 interface add new1 type __ap
hostapd -B /etc/hostapd.conf

First I stop the network manager, which has its own way of messing everything up, then I rename new0 the virtual interface on the physical interface called phy0 (adapt it to your case if yours is not called phy0, you obtain the name from the output of iw list), restart the network manager so that I can connect the virtual interface new0 to whichever AP I have near me.

Now I can add a new interface of type AP on the same hardware (please notice the double underscore preceding ap in the command), lastly I start hostpad.

The configuration of hostapd and of routing/DNS/DHCP depends on your specific needs, and cannot be established a priori.

Best Answer

Related Solutions

Linux – Configure RTL8188CUS for AP and Client Mode with Hostapd

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