mix AP and wireless client

[Dan Williams]

On Thu, 2015-01-15 at 14:15 +0100, Harm Verhagen wrote:
> Hi,
> 
> I'm looking for a way to have simultaneously  an AP and a wireless client
> with a _single_ wifi device.
> 
> I am able to start multiple SSIDs with hostapd, following [1]. This works
> perfectly. I can connect to each SSID. (tested with 4 SSIDS)
> 
> This gave me the idea, that if hostapd can create 'new' wlan devices. I
> (hopefully) can configure the 2nd  wlan0_0 device as a wifi client.

It depends on your hardware and driver whether this is possible.  Look
at the output of "iw phy phy0 info", where you should see stuff like:

	valid interface combinations:
		 * #{ managed } <= 1, #{ AP } <= 1,
		   total <= 2, #channels <= 1, STA/AP BI must match
		 * #{ managed } <= 2,
		   total <= 2, #channels <= 1

These lines indicate what your hardware and driver can do at the same
time.  In this case (Intel 6250, iwldvm driver) I can do 1 AP + 1 STA,
or 2 STA at the same time, but all must be on the same radio channel.

Before starting hostapd (for the AP) and wpa_supplicant (for the STA)
you could create the STA interface yourself:

iw dev wlan0 interface add wlan0-STA type managed

which you can then pass to wpa_supplicant for use as a STA/client.
However, note that if you have restrictions on channel numbers (like my
output above does) you'll have problems connecting the STA to APs on
other channels.

Dan

> 
> Usecase: For a device thats
> 1) sometimes, when near an AP it needs internet acces for itself (hence the
> required 'client' functionality)
> 2) needs to be connected to some other devices, that are only wifi clients.
> (these devices don't needs to access internet, only direct access to my
> device).
> 
> 
> I tried letting hostapd create the 2nd interface(wlan0_0)  by just adding
> bss=wlan0_0  to my hostapd config file.  It does create the device, but
> trying to 'ifup' that as a client (no security yet)  fails.
> 
> 
> Anyone have any clues how to achieve this ?
> 
> host: linux
> wifi: GWF-3M05 IEEE 80211 Wlan module (usb)
> 
> Regards,
> Harm Verhagen
> 
> [1] http://wiki.stocksy.co.uk/wiki/Multiple_SSIDs_with_hostapd
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